From time to time, I try Compiz, to see if how it has evolved. The last time was yesterday (I also switched to the xserver-xorg-driver-ati from experimental).
But as usual, after using it for a few minutes, I can’t help switching back to metacity. I don’t think that Compiz’s visual effects bring anything on the usability POV, and I just find them annoying after the initial “WOW”. Of course, it’s nice to show off, but to do actual work? Are there people really using it all the time?