I've just setup XFCE4 on my uni desktop, and I have to say I'm sold on it.
rate--traditionally a rather weak point with Linux guis, but one which is important in my opinion since 1280x1024 at 60 Hz is horrible, and I don't want to have to mess about in XFree86.conf just to change something like that.
I addressed this point before, and to follow up (now that I have an XFCE install in front of me), you just need to go to Settings | Display from either the panel or the right-click context menu on the desktop.
of customization to get it set up in a way which is as useful as Gnome is in Ubuntu, since Gnome ships with Ubunutu and is set up to play nicely with it and has all the most handy things at your fingertips.
This point really depends on what you want your desktop to do. I have customise any Gnome install to put shortcuts to the apps I use all the time on the menu bar, and to set up my keyboard bindings. At the moment it's fairly annoying to bind arbitary commands to a keybinding in Metacity (the window manager that GNOME uses) - you have to manually edit the gconf registry. It's much better supported in XFCE4 however. From this point of view, I'd say XFCE4 is easier to customise, for the most part.
I haven't ever got XFCE customized at all, or used it for a long period of time, so take what I say with a pinch of salt. It's certainly quick, but I don't know how much difference you'd notice on a modern system?
Things I prefer about XFCE4 (compared to GNOME 2.6/Metacity) * If you right- or middle-click on the maximise button in a window, it will vertically or horizontally maximise the window. This is something I used all the time in GNOME 1.4 / Sawfish, and it was one of the features I missed when I moved to GNOME 2.x / Metacity. * Drag-n-drop printing. GNOME 2.x might have this as well, but I've not seen it. * xffm has some nice features, although it's a bit cluttered. It seems fast as well. Things I dislike about XFCE4: * When moving workspaces to the right, it eventually wraps round to the left. I like being able to hold down F6 (the key i bind to 'move one workspace to the right) and hit the end. * It has an app menu, but you can't drag from that onto the panel. You have to manually create the launcher on the panel. When creating a launcher, it's fairly tedious to find the right icon, as it doesn't default to /usr/share/pixmaps As far as look and feel goes, it uses GTK2 so shares some similarity with GNOME 2. It is designed in a fundamentally different way however (GNOME is very start-menu oriented, XFCE isn't, for example). If you're used to GNOME, that might be a problem - it's too close to what you're used to, yet still different. It feels fast, but so does anything on a dual opteron 250.