I moved to rawhide a few days ago because I wanted to try KDE4.
At first I had some problems because I didn't install all the related packages, actually, I had a lot of problems, ranging from 3 crashes an hour to missing icons.
After I installed those packages, crashes started to happen less often, some icons just showed, but I still didn't like it.
Then I started messing around with whatever settings I have (many settings are missing and won't be implemented until 4.1), and that helped the desktop look better, I had gray around the panel, boring decorations, etc... But now, I have cool glassy edges around the panel, with semi transparent decorations :)
Then it was time to fix the sound problem, I headed to #fedora-kde and asked, thanks to the folks there I have the sound working fine now.
I still have some problems such as not being able to use shortcut keys, and some other problems that I can't think of right now.
In short, KDE4 is OK, not as great as I expected it to be though, and I wouldn't recommend it to anyone at the moment, maybe later when KDE4 is actually released it'll be more stable. I also find not being able to configure the panel a bit annoying, yet bearable.
I have to say that the only thing I really liked in it is the code folding feature in KWrite :D