Don't like iTunes 11. Apart from the unasked-for GUI revision, which made some features just disappear (I mean, Apple knows what we want, so they don't have to ask, do they), it also brought some bugs.
The latest bug I observe is that the play count ("Plays") for some songs just disappears, i.e. the last played date is still there, but there is no play count anymore. Sometimes it's 17 songs without play count, then again there are 92 titles where the play count has just gone.
Maybe this happens when I sync, I don't know.
I have reported this bug to Apple. Please do the same (https://bugreport.apple.com) if you also have this very annoying problem.