I've been using the svn release of KDE 4.4 for a little while now, and I like it a lot. More streamlined and little tweaks here and there to make it feel more complete and functional, give it a whirl and see for yourself!
http://arstechnica.com/open-source/...antic-desktop-starts-to-show-in-kde-sc-44.ars
http://arstechnica.com/open-source/...antic-desktop-starts-to-show-in-kde-sc-44.ars