It is a topside treatment - essentially a substitute for wax. You could do the bottom if you boat was kept on a trailer and not slipped (and bottom painted), but that's not what you are looking for.
Search on thehulltruth.com - there is lots of feedback on there from people who have had it done. From what I've read, you want to have someone who really knows what their doing as it is much more involved than waxing (and much more expensive) and it is critical that you get the application right. I don't think the cost-benefit is better than waxing - again from what I've read. It looks great at first (so does a fresh coat of wax), but doesn't seem to last 3x - 5x longer than wax which is what the cost is.
FWIW, I've had very good results with Collinite Fleetwax 885 heavy duty paste. I apply once a year in the spring after a polish and it lasts a year, but that is in a covered slip. For the non-slip I've been using Woody Wax, but I haven't made up my mind on that one as it doesn't seem to last very long.