O god don't buy it!
One of my friends works for a local marketing company selling this shiz, it's terrible! From what I could tell by trying it on his car, it has poor lubricating properties and offers no protection against swirls or anything. He works 6 days a week, located at a different gas station each week and they are told to walk up to the nicest looking car, spray the stuff on a really dirty patch and start rubbing it off. The more they sell, the better they get paid (and paid quite well I must add- if they sell enough).
I have taught him some of the basic ways of proper detailing and he is actually looking to change departments in that company now - I feel proud haha.
Long story short, I told him that if he put that can of crud anywhere near my car I'd come to his house and key his car.
Stay away from fastwax.