I am having a similar problem, only my Turbo restarted itself (suddenly, I thought maybe it was the 5 update) and then hung. I had to do a hard reboot (power and volume button) and finally after the 5th or 6th try it would open. I switched back to Davlik and the problem is not happening. I am worried about 5 if it only runs on ART?
My screen was hanging on the initial sensor screen, it would not unlock. I could touch the lock/unlock icon but it would not unlock. Even after restart, when there was a message icon, the screen would not unlock. It was very frustrating (on top of that, I had some wireless router issues, so I couldn't get online at home to look up the problem, or contact Verizon. *sigh*).
I'm set for now, afraid to try ART again.
ETA: I had a different number of apps to be optimized on ART vs Davlik, which was very strange. More through Davlik.