Any time we root and otherwise modify our devices, there’s an inherent risk involved. Yes, once in a while things don’t quite go as planned. However, if we’re careful, things usually go well. And we’re usually able to recover when they don’t.
A recent exception to this feeling of security had to do with the TA partition on Sony devices, where unlocking the bootloader would clear the TA partition, its stored DRM keys, and your ability to use certain Sony applications and receive OTA updates.
Now, there is something else to worry about when bootloader unlocking the Sony Xperia Z1 in particular: camera functionality. As noted in this thread (starting with post 4), various users are reporting problems with their cameras after unlocking their bootloaders.
It was eventually discovered that restoring the TA partition seems to fix the problem. So if you must proceed with unlocking your Z1, we highly recommend that you create a valid backup for your TA partition. However, proceed with caution, as restoring the TA partition seems to be the only way to restore camera functionality at this time.