I've posted about this on several threads, I think. I've read several reviews (check out drugstore.com), and it seems that the people who have liked the product are older ladies with dry skin.
I got the Neutrogena kit as a gift, and was excited to try it. However, it broke me out really badly. After a while I tried it again (trying to fade scars), and it was worse. Only after several professional microdermabrasion treatments has my skin gotten better.
Also, you probably will have to keep buying the replacement sponges (mine wore out quickly) and the crystals. These are $15 each if I remember right.