I just installed KDE SC 4.4 last night and I can say that I feel that it’s finally general user ready. The last bug that I felt would prevent average use is now gone. What was that bug? when you pressed print screen nothing would happen. There was a workaround to make print screen work but it didn’t work out of the box. I feel that there are some things that should just work and that’s one of them.
I’m not sure I’m yet happy with the state of the device notifier, and automounting as the UI doesn’t seem perfect yet, but it can now do all the things that are necessary.
There will always be improvements to be made, but I think that if you’ve been not sure about using KDE 4 go give it a try now. (I’m about to find out if I can replace vim with kate’s vi bindings).