Yet another issue with the camera, quite often if while the phone is in a locked state, I press the camera button, the phone should show the viewfinder/camera, but what actually happens is that the camera is actually activated but not the screen. So you think it hasn't started the camera app, so you press the camera button again, only to hear it take a picture.
Sometimes pressing the unlock button brings up the lock screen as normal, but the screen does not respond to touch so you can't swipe up and enter the pin, you have to lock, then unlock it again and then the screen responds normally.