I haven't tried it, but I've seen the infomercial, and it does look quite convincing (though there are a couple of things I think are misleading: 1) Cindy Crawford's skin hasn't changed that much since she was younger, which suggests that what she's been doing is good for maintenance or prevention, not necessarily for 'turning back the clock'.
2) they state something like CC has been using the same type of ingredients as are in the product for many years (and there's also some brief either mention or some other suggestion that the doctor uses injectable versions and/or concentrated versions of the ingredients, not the creams and potions in the kit).
The good news: I've found that Guthy Renker is a very reliable/trustworthy company with excellent customer service actually based in the US! (I get Principal Secret products--which I actually see a difference with--from them), and you can always try it for 30 days (or maybe it's 60?) and if you don't like it, return it for a refund.
The cost of the trial kit is very reasonable (after they go through their whole "we'll reduce the price by XX" spiel, it ends up to be under $30, plus tax and shipping, right?) so maybe worth a try.
The before-and-after photos look like there are actually some results, and not just a case of different lighting/angles/facial expressions making it appear so.