Well I think the lack of redrawing is great. I can move, minimize and restore windows without triggering their UI threads at all, they don't stutter to redraw things. It means I get to have live thumbnail previews of all my windows without slowing anything down (it just reuses the same off-screen buffer).

And Compiz isn't just about compositing gimmicks. I like that I can hold the Super button (the "Windows" key on PCs) and scroll to zoom in, or click and drag to take a screenshot of any part of the screen.