Is this just me? I'd spent literally hours combing through all of my photos to be sure that people were assigned to their correct faces and photos and suddenly none of it is there???
I believe this was planned and mentioned in the b5 release notes. See page 8.
Ah, in that case I don't know if it was planned or not. I always recommend making a good backup of whatever you can before updating a beta but I don't know if Faces info carries over in those.