Even though KDE4.2 looks nice and works pretty much ok, there are a lot of things that'll keep me from using it.
For exampe, the brightness keys on my laptop do not work, because Fn + KEY combination is apparently 'not supported by Qt'. Nice. I know Qt is the bomb and all, but functionality like controlling brightness of my screen should be implemented by using the correct key combinations. Too bad, because I like KDE4, but this is a show-stopper for me.