ZenFone 2 Review: Cheap, Fast, Big, Flawed

ZenFone 2 Review: Cheap, Fast, Big, Flawed

The ZenFone 2 is the culmination of a trend that has been formed ever since OEMs began to focus their efforts on affordability. The Moto G was a game-changer back in 2013, and it certainly is a nice device now — but the game has changed dramatically since then, and users have more than a few options to sate their wishes of a good phone for a good price.


From the ultra-cheap Android One to the flagship-level OnePlus One, you are bound to find the one.


Could the ZenFone 2 be one too?


Before we get started, I must mention that with this review we are attempting to take XDA in a new direction. We spent countless hours discussing not just methodologies to employ, but the philosophy behind what we want to achieve. We are not done yet, and halfway through the making of this review we realised exactly what we need to do: open source the process. There are still many things to be ironed out, and we will announce further improvements when we feel they are completely ready, but this represents the beginning of a new breed of analysis for us.


Our overall goal is to provide an objective and honest perspective on the devices, inviting users to see every step of our review process along the way. In the short term, this particular review should  speak some of the things that other reviewers missed, or deliberately ignored in their pieces. As of now we lack the proper tools to objectively measure certain things that we want to measure, but we will work on improving our methodologies and opening up the review process entirely to provide truthful and compelling reviews in the near future. We also want you – the XDA community – to be an actively involved agent in these upcoming developments, so stay tuned for more updates on upcoming reviews.



ZenFone 2


We covered the original reveal of the ZenFone 2 back at CES 2015 in January, and since then I’ve personally been intrigued as to how such a device would perform. Many reviewers latched on to the 4GB of RAM tag line, but for me the bigger announcement was Intel’s latest Atom line-up. The silicon game on Android is dominated by few players, namely Qualcomm, and the very nature of the industry (that is, high investments into R&D and fabrication expenses that ramp up year-to-year) prevents new blood from joining the crusade. Intel is no schmuck when it comes to processors, and they’ve been ahead of the curve in desktop silicon for a significant while. As such, they are a company uniquely poised to bring their name to the mobile scene, and the ZenFone 2 is the perfect opening salvo.


ASUS’ decision to include 4GB of RAM is also welcome. Many would claim that such an amount is overkill — for most things, it is. But we will see below that it does make a difference in real world usage, and it puts to use one of the biggest virtues of the jump to 64-bit chipsets. ASUS also set out to include a beefy battery, a fine camera sensor, and what they claim is a very color-accurate screen. Finally, the design of the ZenFone 2 is meant to encompass its allegedly high-grade internals in an elegant chassis. We’ll stop on each of these fronts one by one, but here is the quick spec overview of our unit to get us started. (ASUS_Z00AD):


  • Dimensions: 152.5 x 77.2 x 10.0 mm
  • Weight: 170g
  • Dual Micro SIM support (second is 2G only)
  • microSD expansion (up to 64GB)
  • 64 GB of built-in storage
  • 5.5-inch 1080p IPS LCD with Corning Gorilla Glass 3
  • 13MP rear-facing camera with dual-tone LED flash
  • 5MP front-facing camera
  • Non-removable 3,000mAh battery
  • Bluetooth v4.0 A2DP EDR
  • Android 5.0 Lollipop with ASUS ZenUI


Design, Build Quality


The first thing that allured me about the ZenFone 2 when originally covering its reveal was its design: it borrows from other devices in what initially seem like thoughtful ways. The buttons are located on the back very much like on the G3, except that the power button is on the top. The backplate also borrows a faux metal brushed look, and the back speaker grill looks strong and powerful. That is what you initially notice, at least. What I initially felt however, is a different story. This goes back to the unboxing experience, which was not very pleasant and set the foundations for what I consider a consistent theme with the ZenFone 2: masquerading.



The device did not come with the screen foil that we all love taking off our brand new phones; instead, it came with a foil wrap that did not hug the device very well, and the glue attracted dust and other nasties within the box itself. The screen and phone were a little sticky as a result. This is a minor annoyance and an anecdote at best, but the thought and care that usually goes to many unboxing experiences was simply not here, and this is most likely due to cutting costs. After all, when you promise a device comparable to a flagship for less than half the price, compromises must go somewhere.



On a more thorough and first hand look of the device, I was quick to notice just how grippy the back plate was. Moreover, under most light angles, it does a surprisingly good job at emulating metal. What really kills the illusion is the plasticky logos at the bottom area of the device. The back buttons are also akin to the chromey plastic that you used to see on Samsung phone edges, and mine came with a very slight dimple which I assume was a manufacturing defect. Other than that, these back buttons are very clicky and their tactile detail looks nice even if it doesn’t not give as much sensory feedback as other solutions. The dual-tone flash and the camera at the back slightly protrude, but not in a worrying way. The power button at the top is a disappointment, as it is hard to click since the location is simply not very efficient and it does not have enough travel.


The back is removable and reveals access to a dual SIM configuration, one which allows for 2G/3G/4G and the other one simply 2G. For developing markets or roamers, this is a welcome feature that I’ve actually exploited. There is also expandable storage of up to 64GB and unlike many devices, all slots are readily accessible without removing the battery (this is a minor pet peeve that I have with some phones). But you can’t remove the 3,000mAh battery regardless, as much as its exposed sides tease you to rip it out. The large speaker grill is a facade, as it covers a much smaller speaker located at one side of the device. The NFC receiver and power button are built into the removable back, and on the actual body you can only find a sunk button with a covering wrap. I must say that I am very surprised at how well the case fits – it is very tightly attached and it makes the device feel very solid.



The front of the device does not match what many promotional pictures depict it to be like. ASUS claimed this phone to be a 5.5 inch phone in a body of a typical 5 inch phone, but it is simply not true. The side bezels are very large as is the bottom chin, which holds capacitive keys that do not have a backlight but rather a reflective trim. The bottom chin has nice details, but they ultimately take too much space.


Overall, the phone does a good job at mimicking certain flagship trends without bringing the premium feel to the table. It can be a looker under the right conditions, but the phone is significantly bigger than it should be. This does not affect handling for me, however. The combination of a grippy and curved back made it easy for me to move it around for the hand gymnastics any phablet requires for one-handed usability. Taking the phone in and out of pockets is also a seamless experience, a detail that I find very important. If you happen to drop this phone, its tightly fitted plastic body would take the hit better than most premium phones, but its plastic is prone to scratching and despite the Gorilla Glass 3 coating I’ve seen numerous reports of early screen shattering on seemingly harmless drops. Another small thing I’ve noticed is that the display itself gets smudged differently than my Nexus 5, Note 3, Note 4 and Galaxy S3; the smudges are not spread as uniformly, and in general the screen does not seem to have as much ease of finger travel. This could be due to the oleophobic coating solution, but it does not significantly detract from the experience.




Like previously stated, this phone is running an Intel SoC, the Atom Z3580. In a world where 64-bit CPUs go for more than 4 cores, Intel keeps a traditional quad core design. While the Exynos 7420 and the Snapdragon 810 have a big.LITTLE set-up, Intel goes for a higher clockspeed on their single pack with a turbo frequency maximum of 2.33GHz. The big.LITTLE configuration proved its might when it comes to battery saving and multi-threading (although heterogenous multi-processing is still not an immediately tangible reality), but the ARM CPUs featured on both chipsets differ from Intel’s Atom SIlvermont x86 architecture. This difference is something that many overlooked, but I think it is key to understanding the nature – or zen, if you will – of the ZenFone 2. Bear with me for just a few sentences:


Android apps rely on Java-derived VMs, which are platform independent. This implementation is not fully optimal, and to squeeze extra performance (which we all want), developers can opt for native C++ code in their applications using the NDK, being able to touch on platform-specific binaries and further optimize by bypassing Java limitations such as its smaller heap size. Said optimizations mean that ARM platforms – the prominent architecture of Android CPUs – see the immediate benefit due to the standard’s popularity, but the x86 nature of Intel’s SoC cannot exploit it at all. The NDK allows for building apps with code that is native to x86 platforms as well, but not all developers go down this route. To counter that, Intel’s binary translator makes your installed apps ready for the x86 design… with a catch: efficiency in both performance and power consumption take a hit. There are vast resources from the past couple of years that prove that this sort of binary translation yields worse results, some coming from ARM itself. For reference, take a look at apedroid’s comparison of Epic Citadel on translate and x86 native code. We will touch on the meaning of all of this shortly.



Despite this inconvenience, it must be stated that the ZenFone 2 is a great performer, particularly for the price. Benchmarks reveal very good things about it. In many categories, it trades blows with flagship phones, and this is not just due to its Intel CPU, but also due to the 4GB of RAM and other all-around extras. Before going into the benchmark analysis, here’s a summary of my real world experience:




Regardless of its seemingly heavy and feature-loaded ROM, the ZenFone 2 runs like a dream in most operations. App opening and closing is very fast (for most cases, as there are some inconsistencies) and comparable to most flagship phones, and basic navigation commands are extremely responsive. Animations are very fluid all over. When it comes to its RAM (expanded below), I must say that I have never seen a device perform this well; all the hype surrounding the 4GB of RAM in this phone is true, and you can indeed have multiple games open without any of them leaving memory. This device truly does feel optimized for performance, but not so much for stability. Now that those comments are out of the way, this is how we see it compares on a more objective ground. One thing that we must keep in mind is that benchmarks represent theoretical maximums and not real-world performance, and if anything they can tell you just how much a device can be pushed, but not what the median performance is actually like.


We are breaking down the analysis by components, but all parts work together to bring the real-world UX, so do not take any single result as an end-all and consider every comment and sample on real-world performance. To start I want to mention PCMark (shown above), a benchmark that aims to simulate real-world usage rather than abstract algorithms and computations void of tangible impact. The subtests mimic actual smartphone operations, and the results the ZenFone 2 outputs are very impressive to say the least. The Work Performance overall score can top devices like the Galaxy S6 (by a hairline) and the Nexus 6, and it is only in the writing-focused tests that it loosens up. Another impressive aspect is the fact that despite this being a lengthy test (albeit not quite as taxing as other benchmarks), performance stays very consistent throughout with no signs of throttling.


CPU & System

  • Atom Z3580 quad core @ 500MHz (min) to 2.33 GHz (turbo boost)



Basemark OS II System scores put it below devices like the Note 4 and G3. These analyze math tests (integer and floating point operation speeds) as well as the single core and multi core performance of the CPU (by processing a 2048×2048 32 bit image). Being a test heavy on CPU and RAM, this is revealing about theoretical performance but not so in a very extensive way. Despite the 4GB of RAM, the phone does not beat the Snapdragon 801 and Snapdragon 805 devices with less RAM (except the OnePlus One, surprisingly), but it does outscore the Snapdragon 810 on the M9 by a hair. AnTuTu’s CPU breakdown shows its performance being comparable to Snapdragon 805 devices, with CPU integer scores at 4531 and CPU float-point at 4305, as opposed to my Note 4’s 4147 and 4420 respectively. Geekbench (CPU focused) also has promising results, and these are interesting due to the difference in architectures with the competition. Single-thread integer and float-points are below the Snapdragon 805 here, and more in tune with the Snapdragon 801, with the latter being slightly better at float-points. These are limited calculations, however, and do not represent the entirety of system operations. But despite this, I must say that real-world performance is mostly consistent with these rankings (even if not commensurable) and the device fires and loads (mostly compatible) apps like flagship devices of today.



Something worth noting is that, unlike infamous devices in this past year, the device’s temperature did not get too high during subsequent benchmark scores, and neither did it drop in performance. Running multiple System and CPU tests consecutively showed that the device stays at mostly consistent temperatures with equally comparable scores. In a span of 15 minutes of continuous CPU tests like Geekbench (a rather short CPU benchmark time-wise), score sums didn’t drop in a way that would indicate significant throttling, and temperatures consistently remained within 29°C and 31°C. During continuous GFXBench, the highest temperature I was able to record was 35°C. During heavy 3D gaming samples of 20 minutes, this was also an average temperature I recorded except for a particular game – The Witcher Battle Arena – where the device can actually get to 41°C when running at the same settings I typically play this game on my Note 4. Other benchmarks ran even cooler and just as consistently, however. The GPU is typically a temperature culprit, but on the ZenFone 2 this trend is quite marked.


GPU & Gaming


The GPU is where things change, although not necessarily for the worse in real-world usage. The GPU included in the ZenFone 2 is the PowerVR G6430, the same type of unit found in Apple’s A7 chip (and thus, Apple devices like the iPhone 5s), clocked at 533MHz. For those of you into gaming, let me tell you that there is little to worry about — most games run very well on this device. Before jumping onto benchmarks, I want to mention frames-per-second in the games I tested (measured with Gamebench) were great. Modern Combat 5 stayed tangent to its engine’s 30 FPS limit. The Witcher Battle Arena (a favorite game at the XDA office) did not perform as well, though, and it heated the device significantly more than its regular output would suggest. For those of you wondering about Asphalt, the implied gaming benchmark of Android: it surpassed 45 frames per second, but this is irrelevant for comparison as many devices see their framerates in this game artificially capped to 30 (particularly Snapdragon 805 and Snapdragon 801 devices). In general, I would say that gaming performance can be on par with devices from early 2014 such as the OnePlus One, but not as consistently (most likely due to optimizations).


On the more technical side of things, I see the GPU being one of the weakest links of the processing package. GPU-intensive tests and applications are really the only tasks, apart from charging, where I saw the device get warm enough to consciously notice it. Basemark OS II graphics tests put it below devices like the OnePlus One and Galaxy Note 4, painting it as weaker than the Adreno 330 and 420 in the Snapdragon 801 and 805. GFXBench 3.0 scores (which mostly mimic actual 3D rendering scenarios) reveal a more positive story: the (offscreen) performance of the ZenFone 2 is below the Adreno 420, 430 and the Mali-T760 in the S6, but the Intel Atom’s graphics output in many of these tests looks to be comfortably close to that of the Adreno 330 in the Snapdragon 801, a chip that still holds up its own very well. Once the resolutions get factored in, however, performance is comparable to newer flagships.


For the price you are paying, this is not bad at all, and because of the 1080p screen, the on-screen and real-world results are similar to Snapdragon 805 devices that push a hefty 1440p screen. However, keep in mind that the additional RAM and the different type of CPU do not make the results directly commensurable. To illustrate the kind of difference you see from the jump from 1080p to 1440p, I reduced the resolution of my Snapdragon Note 4 and ran the benchmarks again (comparison to the side). The percentages tell the story better than I ever could. This GPU can certainly dance the dance, but it does not get as close to the current GPU leaders as the CPU does (at least not in raw power).


On Storage and Memory


As far as memory goes, the flash storage result on Basemark OS II is leading class, with a score of 1,307 which surpasses most phones except the memory juggernaut S6. AndroBench’s storage results, however, are modest at best. This is a particularly worrying aspect that crippled the longevity of ASUS’ own Nexus 7. On average, sequential read and write speeds lay at around 137MB/sec and 70MB/s write respectively. Random read and write are at about 20MB/s and 5MB/s. These scores put it at the bottom tiers of memory solutions in recent history. and devices like the Galaxy S6 can achieve random reads of over 70MB/s.


RAM is another story: the app-holding capabilities of this phone are tremendous, and it puts TouchWiz Lollipop devices like the S6 to shame due to their software faults (which have just recently been solved in our forums). Its RAM is dual-channel DDR3 instead of the newer DDR4 in recent flagships, but multitasking performance is top notch regardless. Another thing worth noting: the phone does not seem to slow down when installing or updating apps despite the mediocre storage, which is a pleasant surprise. But as far as keeping things in memory goes, the one thing I notice is that there are still launcher redraws, something that I find hard to grasp my head around. Overall, though, this is one of the memory kings, if only due to the RAM capabilities pulling the weight.



  • 5.5-inch 1920×1080 IPS LCD panel


ASUS loves to tout the ZenFone 2’s display, and the promotional video they stored in the phone to show off its capabilities is full of self-praise. For a $200 to $300 dollar phone, this is a good display. However, the tremendous advances in the competition’s flagship phones are are not seen here. The 1080p display does not have the best pixel density, and neither does it have the best brightness. On maximum brightness, it is just as readable as my Note 4 in direct sunlight, but the latter takes the edge when its auto mode boost kicks in. I also compared it to an iPhone 6 and an iPhone 5s, both of which featured better maximum brightness.


As far as colors go, the screen is not very saturated and while its base colors are not very distorted, they look dull when compared to the accurate screens of the Note 4 and iPhone 6. If you have a good-screened flagship to compare it to, you can easily tell that its color reproduction has lots of room for improvement. This is particularly noticeable when consuming media with mixed colors. Solid and basic color media (as seen in certain cartoons) does not seem to show quite as big of a distortion, but without accurate screen-measuring tools it is hard to be certain. For an LCD display, the black levels are really good, and the contrast ratio is surprisingly high —  from what I’ve tested it seems to be very close to the iPhone 5s.




White backgrounds do not look as accurate as any of the devices we compared it with, but color casting is on the low side on viewing angles that would absolutely distort other screens at this price-point. Something worth noting is that the adaptive backlighting in the display can have odd brightness mutations when switching from certain colors or from all-black to all-white screens. This is noticeable with the naked eye and is sometimes visually disrupting, much like Samsung’s adaptive screen. There is also a built-in app to calibrate the screen’s temperature and saturation in case you are not happy with it, which can potentially lessen whatever discontent you have with the display. Overall, for the price range the ZenFone 2 competes in, this display is surprisingly good.



The misleading speaker grill pretended to be bigger than it was, and its performance makes the reason for the compensation very obvious. The speaker is decently loud, close to my Note 3 in output and it can certainly serve for most jobs, but it sounds tinny and at times muddy. It is worth noting that of all my reference phones – Note 4, Note 3, iPhone 6, 5s and Galaxy S3 – none have earth-shattering speaker quality, but I would pick any of them (except the S3) over the ZenFone 2. Headphone audio output is rather muddy, and if you are an audiophile you will find that other OEMs have far better solutions.


The microphone is also mediocre, but it is good enough to be understood on a phone call. In fact, the phone call quality on the ZenFone 2 was surprisingly good and it held its own in the loud streets of Buenos Aires and Minneapolis. Overall, the audio solutions in the ZenFone 2 do their job without significant merits nor transgressions. In the future we will find ways to measure audio more objectively.



  • Rear Camera: 13MP 4:3 (16:9 10MP Default, used for testing) F/2.0 Aperture
  • Front Camera: 5MP 4:3 (16:9 4MP) F/2.0 Aperture


The Zenfone 2’s camera specs would have you believe more than it can output. I’ve seen users and journalists blame the Toshiba sensor found in the rear camera, but after many pictures I concluded that this is not really so much a problem of the hardware modules themselves, but rather the software decisions and implementations made by ASUS. For years, smartphone cameras saw two big complaints that affect picture quality: sharpening and saturation. The ZenFone 2 grabs these two aspects and blows them out of proportion at points, but not always. To put it simply, some pictures are way too colorful and the end results look as if they applied a cheap HDR algorithm, regardless of it being on Regular Auto and not HDR mode. This is a shame, because I feel like ASUS put together a moderately coherent viewfinder UI with a decent amount of features and very tight manual controls that let you tweak the shutter speed, white balance, EV, ISO and focus. With these options at your disposal, you can take good pictures out of this phone, but the phone plots against the possibility.




Even without professional shooting skills, the Auto Mode does have good moments. But for the most part, the camera experience in this phone is not optimal, and at points it gets downright frustrating. Something I cannot emphasize enough is just how inconsistent the focus and exposure algorithms are. Plenty of phones can efficiently adjust the exposure according to your focus point, yet the ZenFone 2 does a very poor job at this, and a single landscape can have two ridiculously different pictures with a pair of not-too-distant focus and exposure points. Focusing is actually not too slow, but it can get locked in blur rather easily (as seen in the sample video). That being said, even on auto-mode you can tweak the exposure bias. The camera is also very slow at taking a picture, and without image stabilization, this can lead to slight anxiety whenever you need to capture an event quickly.



The pictures do have a fair amount of detail to them, but this is mostly because of how much the ZenFone 2 sharpens your pictures.  It attempts to bring out detail that is just not there, and the results can be a bit distracting. Distant objects can get rather blurry because of this, and at medium lighting text can look a little more pixelated than it should. The 50MP resolution mode does not really help much with overall quality, and despite taking significantly longer than a regular picture, the end result does not offer anything other than additional resolution which lacks actual detail density. Medium to low lighting shots are not bad, and I actually found the colors of some of these shots better than what I could output on the Note 4. For the price tag, noise is surprisingly low on non-ideal conditions.




Video is a similar story, an inconsistent one at that. Despite setting the video settings to maximize quality, the bitrate remained rather low (15.55 MBps on average) when compared to my 2014 reference devices. You do not get 4K nor 60FPS 1080p recording, and the same exposure algorithm can also ruin your videos (as seen in this sample above). That being said, I have taken some decent clips with this phone (just look at those kittens below!), but for the most part there is not much here. The recorded audio suffers from the same problems seen in regular sound recording, and it is worth noting that because of the lack of OIS the videos come out very shaky.




Battery Life and Charging


This is one of the aspects of the ZenFone 2 that is also very inconsistent. On some days, I was only able to get 2.5 hours of SOT (screen-on-time), while on others I was able to surpass 3 hours (on a 16 hour period). On others days of similar usage I barely broke past two. Idle battery life is also unstable, but I’ve had 0.5% drain per hour on overnight idle discharges on some nights. This is on Wi-Fi, however, and I notice that when idling on 3G and 4G the device seems to drain twice as quickly. This is an extremely sensible topic for a lot of people, and most of my results seem inconsistent with a lot of other reviewers, which also seem inconsistent with themselves. I also want to note that I only had a couple of days of LTE test driving with this phone due to real life complications and developments, and most of my real-world usage was done under 3G.


We speculate that the inconsistencies lay not just on base Android inefficiencies (Lollipop) but are also due to the previously mentioned binary translator. To put it simply, this phone’s battery drain feels completely different than that of other phones I have tested. I attribute this to the fact that I was able to get a low standby time (after some optimizations and disabling bloat), yet certain applications would bring very quick battery drainage. Despite the x86 architecture and less powerful GPU, gaming time was rather remarkable anyway: over 3 hours of Asphalt 8 on the highest settings, and a bit more than that of Witcher Battle Arena on the lowest settings (only way to make it bearable). Some days, though, idle battery drain can hit over 3% drain per hour on Airplane mode, and sometimes more than that too. The battery life has been puzzling to say the least, but I did break the 4 hour screen-on-time on a particular occasion of my usage throughout a 16 hour time-span. It is worth noting that most of the battery drain falls within the Android Kernel and Android System, with many Intel processes listed that could have something to do with it. We will update you whenever we find out more.



Battery life benchmarks like PCMark show inconsistent results as well. The highest (out of 3 tests) Work Battery Life I got was 5 h 26 min, and the bundled scores also surpass those of my highest regular benchmark despite these battery tests running on a loop for very longs period of time. This is with bloatware removed on the latest software update. Most importantly, I want to stress on the fact that this benchmark is still misleading, and even with continuous usage of my actual typical suite of applications, I cannot net that kind of screen-on-time. Even then, this result is below all my reference devices bar the S3 (which I could not benchmark, but I know for a fact that it would not properly compete). This is yet another puzzle piece that has me scratching my head, and I hope to dig into it to find out if it is related to x86 optimization. A very good sign that this benchmark shows, however, is that battery consumption and processing output stay constant and consistent throughout the extensive testing, which is a plus for the processing package inside.


The fact that battery life was inconsistent struck early on, and because of that I struggled to find a way to quantify it respectably. I will expand on this with more in-depth testing to see the difference between the drain of binary-translated apps and those that have native x86 code. For now, on a broad stroke I can say that it can last a waking day with about an hour of Youtube, an hour of browsing/texting/social media and about 30 minutes or more of intensive activities such as gaming and video recording – a typical usage pattern for me. In my 10 days of practical daily driving, I only found myself reaching for the charger before the end of day twice. The device does charge reasonably fast due to its 18W charger, which can fully power up the device in about an hour and a half from its dead beat. It is a little on the chunky side, but you can also use Quick Charge 2.0 chargers to obtain very similar results.


A Note on System Stability


Out of the box, this device showed more bugs than I would have expected. Throughout the three software updates I’ve received, though, stability did noticeably improve. ASUS had OTAs with changelogs that suggest a big lack of polish, especially for those very early adopters. This makes me question many of the earlier reviews that did not list, mention or seemingly encounter the apparently widespread and more obvious or dangerous bugs.


To list a few things that I’ve found with the device in my testing (all of these have been documented in pictures or video): a couple of times it simply froze with no solution but a reboot. Some video-chatting apps like Hangouts can have slight visual shake-ups when going back to a video conversation. On some (rare) occasions, apps like Google Drive feature artifacts at the bottom of the display, which are not static and morph every time the app is drawn on the screen. The camera was very unstable on the earlier versions, and not only did it crash but the phone also informed me that it was aware of the problem and told me to reboot the system to fix it. A random app also crashed most of the times I initiated screen recording (as seen in a featured clip). Finally, the System UI crashed entirely on me twice – once on the first software build, and once in the latest one. I also did factory resets in between the first 2 of the 3 software builds, and re-did most of the more technical tests on them as well (virtually no variation).


These problems have been underrepresented in the blogosphere, but the fact that ASUS has been pushing out so many software updates in such a short span of time should be enough to let you know that this was another infamous case of unfinished software. It is commendable that the company responded to the problem by quickly issuing iterative fixes, but even on the latest software build we tested the device still saw a few minor issues. These are not extremely frequent issues, but if you do care about the stability of your device it could be something to keep it in mind or, at the very least, do some extra research on the subject.


Software UI/UX


The ZenUI is not the kind of UI that western markets gush over, and in a way it feels like it is not aimed at a specific demographic like others look to be. The OEM ROM as a whole borrows heavily from its competition, not just in features but in design philosophy. One of the first things you will be quick to notice is the fact that this phone is packed with applications that nobody asked for. “Do it Later”, “Mini movie”, “Omlet Chat”, “Photo Collage”, “Splendid”, “Up”, “What’s Next”, “Zen Circle”, “50+ Games”, “TripAdvisor”, “Clean Master”, “Dr. Safety”, and more.  There is even a “Mirror” app that is just what you would expect: it just activates the selfie camera. If that’s not silly enough, ASUS did not get the memetic memo, and the included Flashlight application has permissions such as “take pictures and videos” and “full network access” (despite the app not actually needing any of this). Now the good part is that you can uninstall a surprisingly big amount of these, and you can disable the ones that are indestructible.


The bloatware is something that you want to disable as fast as possible, as it tends to clutter your notification bar with service prompts. Many of these services also want you to rate their app store entries with varying degrees of intrusiveness. What’s more surprising is that default system applications do this too, particularly the camera. The Launcher itself also has a big “Encourage us” rate button hidden in the home manager. This is not a complaint, but an observation: ASUS seemingly put together as much as it could in here, and the first explanation that comes to mind is for cutting costs. One thing that I found funny is that after activating the ZenFone 2, my Play Store app list was filled with ASUS app entries.


As far as the actual UI, it is a little on the blown-up side. Buttons, texts and icons are big and colorful, and the notification panel is smaller than it initially looks to be. The quick toggles are, by default, very crowded. Luckily, you can customize these to your heart’s content and remove many of the somewhat nonsensical buttons. Customization in general seems to be a strong point of the Zenfone 2: its theme engine can reach many nooks and crannies of the System UI, and it can tone down the default theme’s over-the-top elements in a pinch.


However, contrary to what I’ve seen it made out to be, the theme engine is simply not as good as that of many ROM competitors, nor solutions that are popular on XDA. The layouts remain rather static as in many OEM theme engines, but the biggest problem is the lack of 3rd party backing as of now. The ZenFone 2’s XDA Themes section is almost barren, and the built-in and ASUS-provided themes can be quite the hit-or-miss. I do commend ASUS for making an extremely customizable Launcher that can even take in custom icon packs — but make no mistake, if you love and are used to NOVA, you will probably remain there.


The ZenFone 2 has some very thoughtful design decisions in its UI, as it allows you to configure smaller functional details that other OEMs often miss (for example, enabling or disabling swiping before accessing a secure lockscreen). In regards to the feature set, the kitchen sink approach can benefit some users as there is some legitimately useful software included, plus most useless bits can be disabled. There are useful features like  screen mirroring to cast your phone on your computer, a remote link to control your PC wirelessly, and smaller additions such as tapping volume keys to fire up the camera from sleep, or  the one-handed mode (more useful than it should be, considering the ZenFone 2’s bezels). Double tap to wake mostly functions like you’d expect it to, but it does seem to become unresponsive at times. I personally love the fact that receiving consecutive phone calls from the same number can ring the phone despite it being silenced. Some software additions are simply pointless, however, and things such as a RAM booster on the first 4GB RAM phone makes us question many thought processes behind the ZenFone 2’s making – it simply does not need such a silly thing.


The resulting UX of the ZenUI is ultimately pleasant once you make it your own. For such a cheap phone with such a feature-loaded skin, the level of smoothness is absurd both in and out of apps despite the previously mentioned complications of the x86 architecture. The RAM adds a very noticeable advantage, and I sometimes notice the difference when grabbing one of my other devices. While the interface itself is not the prettiest there is, ASUS went out of their way to include ways for you to change that, but their theming engine will ultimately live and die on whether it manages to obtain third party support.


Rootability, Future Proofing and Other Thoughts


Despite the shackles of locked bootloaders [UPDATE: XDA found a way!] the ZenFone 2 can be rooted, it can run custom recoveries and it can also have the Xposed Framework installed. You can find more information about these developments here. These are all very lucky breaks for the XDA community, but none of it makes for extensive future proofing. As of writing this, there are no custom ROMs for the ZenFone 2 on its Android Development subforum, and no real mods in the Themes and Apps section either. Due to its x86 architecture, development, optimization, modding and general hackery can prove to be troublesome or unpredictable, especially on a base system that already proves unstable by default.


That being said, I am looking forward to seeing this phone develop: ASUS has been giving it plenty of attention, and while it still doesn’t run Android 5.1, the iterative OTAs have dramatically improved the system on some key fronts. If anything, this shows a relative commitment to the phone on ASUS’ part — if only because they must sustain one of their key flagships in light of early and growing pains. Moreover, while the Intel x86 processor found in the ZenFone 2 is not the most natively supported and does not make for the most stable and consistent app experiences right now, things can naturally improve over time. And it might hold its own for long not just because of the strong SoC and the 4GB of RAM. Consider the following:


Android’s ART replaced Dalvik for many reasons, some of them being that AOT trumped JIT compilation and that Dalvik’s garbage collector was inefficient. Ultimately, it aims to improve app performance and the results have been widely discussed ever since ART’s original optional implementation on KitKat. With better performance and less of a need for native and platform-dependent code, the x86 architecture can benefit as apps become more efficient and do not have as many ARM hooks that need to be translated by libhoudini or whatever method of binary translator that gets put in place. Moreover, developers can port their ARM-based NDK applications to x86 and avoid binary translation altogether for more efficient results (some documentation by Intel can be found here). We hope that ASUS does bring further ART optimizations from more recent and upcoming Android builds to strengthen the process.


Final Thoughts


In case you haven’t noticed, there are two major themes throughout this review: inconsistency and pricing. On one hand, the device performs rather inconsistently in aspects such as battery and camera performance. Its SoC is also more unpredictable than others in terms of output, despite the fact that the CPU does not show prominent throttle nor high temperatures in intensive tasks. We attribute it to software issues, incompatibilities and lack of optimization. It is just odd to see Asphalt 8 performing better at max settings than much less intensive games, and the whole situation is bizarre when I compare it to my other devices and see a different story. But in the end, performance is still top notch in real-world usage and is actually one of the better things about this phone. Which takes me to the second theme: price. For the price, performance is amazing. There are many competitors that are offering similar packages, mind you. WIth the OnePlus One’s price drop, competition in this bracket became even fiercer, and the Snapdragon 801 in the OnePlus One is a proven silicon warrior. But even then, the ZenFone 2’s processor holds its own.


There are many things to love about the ZenFone 2. Its design actually triggered conversations when I came back to Argentina, if only because of how different it looked from everything else in this market. I’ve personally gotten used to the back buttons and the fit of the ZenFone 2 and now wish that my other phones offered me the same level of handling. But despite this, the phone cannot fulfill its mission of masquerading as a flagship device. When you put each of its aspects under the microscope, look past marketing and PR and then compare the results to other devices, you realize that there are very clear cut corners put in place to achieve this price point. One would could argue that comparing it to a flagship is not fair, but these are the grounds it competes in. When compared to virtually all cheaper alternatives, this phone is practically a no-brainer, and it bests anything I’ve seen sub $200.


So I will say it again; for the price, the 4GB ZenFone 2 is a great package. But even that only takes you so far — the ZenFone 2 model with 2GB of RAM might actually be a better alternative for those who want an even better bang-per-buck. While I absolutely love the 4GB of RAM (mostly because it finally makes good use of the newfound 64-bit nature of Android), it looks to be the most tangible benefit that the $100 upgrade nets you. The processor looks to be a little more efficient as well, but the UI already runs like a dream so I cannot see it impacting performance in a way that would justify such a substantial additional investment. Storage could be a concern, but with a microSD slot it is not as necessary as it is in other phones. There are things that need serious revision still – namely some bugs and battery performance – and we don’t know if they will get addressed in due time or at all. But as it stands right now, the ZenFone 2 is worthy of many wallets, and all its little extras (like a 100GB bump on Google Drive for 2 years) add up to a neat package. Whether that worthy wallet is yours depends on how much you value other flagships’ advantages and commodities, assured future proofing and XDA development… With mere promises of a bootloader-unlocking tool [UPDATE: XDA found a way!], anyone who enjoys the virtues of our community must think this purchase through very carefully.




About author

Mario Tomás Serrafero
Mario Tomás Serrafero

Mario developed his love for technology in Argentina, where a flagship smartphone costs a few months of salary. Forced to maximize whatever device he could get, he came to know and love XDA. Quantifying smartphone metrics and creating benchmarks are his favorite hobbies. Mario holds a Bachelor's in Mathematics and currently spends most of his time classifying cat and dog pictures as a Data Science graduate student.