I've used a similar service at our DVD rental store before selling some CDs on Ebay.
I can't show comparison photos as I don't have the discs anymore, but I can say that for discs with shallow scratches or scuffs it works a charm. The disc comes out looking near-new, and plays like it as well.
As for ones with deeper scratches... The deep scratch remained, but it did fix up my skipping issue. So the CD became functional again at least, and I was given a discount for them not being able to remove the scratch.
So my experience with them has been pretty good
