KDE 4.x's default theme has been getting more aesthetically pleasing since 4.3. I was never a fan of the black bottom panel in the earlier versions. I'm downloading Mint 8 KDE x64 now, so I might update the pre-installed 4.3 to 4.4 to try it out.
I still can't decide which desktop environment I prefer (Gnome or KDE). Both have things that bug me, although KDE's quirks are probably fixable quite easily (I can't stand the bouncing cursors most distros use). Gnome's lack of ability to control mouse wheel scroll speed is appalling in 2010 when we've had mouse wheels for over a decade.