Couple of years ago i tried KDE 4.x and it simply didn't work. Crashed a lot, simply missed painting windows some times ... didn't have apps ported to it. and i _had_ to go back to gnome.
Then came unity, it kept getting bette although i never could get used to the half hearted OSX emulation. Broke my normal workflows in a way that i had to change the workflow for the sake of the tool. Bad but livable.
Ever since Ubuntu 12,04 though unity just keeps crashing on me. Its actually visibly slow, dash takes for ever to come up.
The only other option i had was to go back to gnome. But gnome people are horribly re-designing everything for some imaginary person impossible to describe. I mean the justification for removing minimize was that they had two users who agreed with it. Talk about sample size here. Neway gnome was out of question.
I gave up so badly i that i considered switching back to Windows7 (which has gotten better every year btw) + cigwin. Horrible thought but still better than any other choices i had.
But then came the kde 4 and i am at home again. Fast, bugfree, mostly complete with few annoyances i can live with. The only complaint i have is its default theme is still somewaht short of being professional. A complaint i had since kde 2.0. But its ok.
Thanks team KDE for sticking up with the development and no matter how much I ranted about you in the past keep it up.