If the only complaint from the reviewer is 'SCAM' then they just can't read the English language; or choose not to read, and just click*click*click through the pages.
Everything is fully explained when you sign up.
That being said, it's not worth it. Doesn't really save you that much money, takes forever for most checks to get back to you, and the responsibilities are put on you. There are much better services out there.