For me kde is running fine, when i was switching from gnome2(didn't like gnome3/unity) to kde I was a bit afraid that I would encounter many bugs after reading many comment here on phoronix but it worked better than I expected(not more than gnome2).

It could be hardware dependent if kde works good or bad for people, not necessary faulty hardware(in a way yes but) but maybe only not as good drivers and stuff.

Running Kubuntu 12.04 if it matters, works good for me, but ymmv.

But what i really want to say is, don't listen too much on all complaints on kde, instead try it out for a while and see if it works out for you, if not, try something else that is the beauty of open source