Reports are surfacing that Sony Xperia Z1 owners who unlock their bootloader face being unable to use the camera. A number of users have said that once the phone had its bootloader unlocked, they were unable to use the camera functionality on stock firmware, despite working without issue previously.
The only way around this is to back up your TA partition (to save your DRM keys), prior to unlocking your bootloader and then restore it if you want to use the camera. The Xperia Z1 is not at the moment listed as a supported device on the Sony Mobile unlock bootloader site, but then again neither is the Xperia Z Ultra and no Z Ultra owners are reporting similar problems as far as we are aware. Prospective owners beware, if you want to tinker with the bootloader, make sure you back up the TA partition first.