I have one and it works but only a few times on each cd, some cd's just wont repair
The bottom of each cd is actually coated with a hard wax solution, if it scratches then you can remove some of the layer using the cd cleaner, however eventually the layer runs thin and you are out of luck, so it depends what the cd is worth to you, also depends how badly you treat your cd's....i suggest trying to buff the scratches out with a small amount of toothpaste and water first