Well, I really just downloaded KDE because I wanted to try it out, but there was a pretty big down side: now I don't want it anymore! I had read in an online article about Ubuntu vs. Kubuntu that the reviewer had settled on a dual boot between the two because he likes a "clean install." Now I know what he meant. When I downloaded KDE from the repositories, it added all of KDE's programs, not just to KDE's menus, but to Gnome's menus as well. So what began a very easy to read, manageable list of programs became an explosion of "k" games, applications, clocks, timers, etc. I edited the menus in Gnome to reduce this factor, but I settled on removing KDE altogether. The problem is, what was a one-step installation process is now a multi multi multi-step removal process. Maybe with my next Ubuntu upgrade I can remove these in some automated way!
Oh, and here's a similar take on Gnome vs. KDE on Linux.com.