What can I say? It kicks ass. Here's the Gnome desktop environment:
http://sagittarius.destrealm.org/bshelton/screenshot_2006-07-17-03.png
Drop-shadows on the Windows vis-a-vis MacOS are also supported. Here's a shot of the xcompmgr drawing the shadows on my laptop:
http://sagittarius.destrealm.org/bshelton/screenshot_2006-07-12.png
I don't have the latter on my desktop yet, being as Gnome 2.14 supposedly has on that is integrated--but not enabled. I'm not sure I'm quite willing to try it yet =)