I can't decide: on the one hand kde 3.5 is very stable and on the other hand 4.0 looks good, is usable but still has some issues. For me kde 4.0 does a good job and but 4.1 will be much better when it is released and I will upgrade then.
Currently what i don't like is that I have so many kde3 apps installed

and that i cannot sort my favorites in the start menu