"I used to be a KDE user. I thought KDE 4.0 was such a disaster I switched to GNOME. I hate the fact that my right button doesn't do what I want it to do. But the whole "break everything" model is painful for users and they can choose to use something else.
I realise the reason for the 4.0 release, but I think they did it badly. They did so may changes it was a half-baked release. It may turn out to be the right decision in the end and I will re-try KDE, but I suspect I'm not the only person they lost.
I got the update through Fedora and there was a mismatch from KDE 3 to KDE 4.0. The desktop was not as functional and it was just a bad experience for me. I'll revisit it when I reinstall the next machine which tends to be every six to eight months.
The GNOME people are talking about doing major surgery so it could also go the other way."