KDE

Its Full of features
Powerful , Stable (after 4.3.0) , Beautiful and ...

one of the useful DE's

The best thing ever :) Watch KDE become the most impressive open source GUI... perhaps even the most impressive GUI full stop! :)

Well i liked it & used it for a year and half BUT i believe GNOME is more stable & productive (@ least i am.) .
Next version to try will be KDE 5 :D.

KDE 4.3 is the most innovative DE. Kudos for finally trying to change the concept of "the desktop" that has been around since the Apple Lisa.

KDE is the most beautiful and most productive DE in Linux

Ugh, I installed a KDE app and now OO won't get off the KDE theme. Horrible, horrible desktop environment in my opinion, too W95'y for my liking - I'll take my Darkbox GNOME anyday.

KDE is awesome, I used to use GNOME
used Xfce short-term
hate Fluxbox
but 4 is lacking features

KDE 4 is great. I hope they add more features in the future, apart from that 5* .

Great desktop environment but lacks features KDE3 used to have...

Great desktop environment, in my opinion the most polished of all desktop environments. Polished by looks and effects, but also because of the big amount of KDE-programs available. There is an app that fits in the desktop for every task.
The widgets on the desktop are a nice feature, which other desktop environments don't have.

Annoing point of KDE: its customizability. If you like the standard looks (like I do), it's perfect. But if you don't like the big, bold and toyish look, it is not so easy to change that everywhere. It is only possible to make small modifications, like a different window manager theme.
So it's a bit like OS X: love the standard look of it, or don't like it at all.

Excellent desktop environment.

Excellent desktop system

should be merged with Kded4...