I decided to give the O developer preview a shot this weekend, and so far the only problem I've had has been with the screen lock. I don't know if the animation is messed up or if PINs aren't working on this preview, but after a restart, I got stuck in the number pad for entering a PIN. It's like the Enter key on the pad wasn't working. After a few minutes of pressing damned near every item on the display, a poke on the Power button cleared it for some reason. So I decided to go with no screen lock for the time being. Shame since the fingerprint reader seemed to be working fine.