I have tried it many times and I do like it since it reminds me of old KDE 3.x. It is very fast and light, it has all I need (panels, system tray, desktop icons, applets, whatever). And it has a standard design concept (unlike recent weird design ideas by Gnome and KDE).
Didn’t use Xfce4 as a main desktop environment since I was pretty happy with Gnome2, but now things have changed :)
Update: screenshot attached to see how a desktop should look like ;-)