I upgraded to Debian 6 Squeeze last weekend on my desktop. I was very excited to get some more up-to-date packages (git, gcc, kernel, and chromium) but I'm disappointed by KDE4. Yes, I realize I'm a few years behind the rest of the world coming to this conclusion but that's the curse / blessing of Debian stable.
I had been using KDE3 in Lenny. It did everything I wanted and generally kept out of my way. KDE4 is completely different, in a very bad way. My computer isn't slow, although it is 4 years old, but KDE4's out of the box configuration was way too laggy.
It's back to Gnome for me and I'm actually liking the configuration of it that comes with Squeeze. It does what I need, was quick / easy to configure to my liking, and it gets out of my way. That's how it should be.