Just installed xfce on my 2 laptops yesterday. Performance is great ... the video works like it should ... and it's very, very configurable.
No huge issues yet. I'd prefer to have the option to be able to set up dual monitors in extended mode, and there are other minor issues in dual monitor mode.
Also, there seems to be a conflict between the xfce screen saver and the gnome one. I have my video player set to prevent the screensaver but it still came on. For now I've just turned off the screensaver in gnome. Inelegant but it seems to work.
I may not use gnome/unity that much more anyway. gnome-fallback is a lot faster than unity but it's woefully non configurable. If there's a way to set up launcher buttons there I never found it, andd I was very motivated to do so.
Definitely more to come when I've used it enough to be able to phrase questions/problems coherently.