It's not like new - the scratches aren't eliminated, just buffed down and filled in. However, things do look a lot better, and I think it's worth the (on sale) price. Of course, I also have two iMacs (one quite old, one new) that can use it, as well as an Apple Cinema Display, so I was able to justify the purchase more easily.
Basically, it helps a LOT, but it won't make it "like new"....