I have been running Compiz (and now Beryl) pretty much since it was possible to do so with any degree of stability.
Pity you weren't at the last kit meet or you would have had an opportunity to play with it.
Mostly it is just eye candy, some of it is rather overdone and pointless (floppy windows) but other things are actually quite useful (expose type unlayer windows, live thumbnails when you hover over minimised apps, swap desktops taking active app with you etc etc) Also if set up correctly it comes with very little system overhead (consumes a bit of RAM but apart from that I don't really notice it is there)
Most of the bugs relate to things like running other 3D apps on the desktop, video was also a bit of a problem for a while. The later seems to have been fixed in beryl and the former can be worked around with a wrapper script.
I am happy to bring my box to the next kitmeet at Syleham if there is sufficient interest from people to see it again.