I have never tried it.. I am not sure that it would be my style at all, but I have given thought to at least being open-minded to it and bumming it off a friend to see what it is really all about.
I do have one friend who has used it, he was significantly overweight, and he really does look like the before and after pictures you seen in the commercials. His success with it definitely gives it some appeal for me, but I have to truly enjoy something to stick with it, and I am worried the fun factor will be absent in P90X for me.