As a long time user of KDE (12 years or so) I finally got sick of the bugs - especially from 4.
I decided to try out Gnome a year and a half ago on one of my desktops. I've taken my time adjusting to it, and have come to appreciate it. It. Just. Works.
Myriad networking issues? No more. Enabling Compiz? No sweat. I just finished converting my last machine to Gnome two nights ago. My computer is like new, seems much less bloated.
I've always thought KDE was a good switch for Windows users, and Gnome for Mac. My kids, lol, get to start with Gnome.
Folks who say KDE is stable and proven? Crazy. True, it doesn't bail out like Windows, and it does work...mostly. Admittedly, perhaps it is my distro's implementation of it. Who knows. However, I'm much happier with stable, functional, usable, and friendly Gnome than 'pretty' with KDE.
Someday, in a few years, maybe I'll consider KDE again. If they've actually prioritized bug fixes over eye candy - especially networking. It'd be nice if they threw in audio preview too, like Nautilus - I find that handy.