I know many people who have used it. Basically what it comes down to is exercising/training the body as a whole entity rather than selective training the body broken down in individual muscle groups. You still follow a training routine but it is not as specialized as selectively targeting one muscle group at a time per bodybuilding standards. Think of it as overall core training, if you like that new age "core" slang that every PT and their Balleys wannabees harp about.
A lot of the training is through compound movements designed to strengthen the body as a whole. It is (supposingly) for overall physical improvement, not just for muscle hypertrophy or adding some weight to the bar powerlifter style. Mostly it is focusing on stimulating the entire central nervous system through training so the effort is synergestic for the body as a whole.
I see a lot of triathletes, firemen, and track jocks following it here in South Florida. I don't know exactly the principles the program advocates, but I see them doing some of the exercises. Mostly in groups of 3 -5 people each lead by a 'trainer'. But then again, I see some people with a log book (or whatever) doing it by themselves. I don't know if you can buy the program or if they have someone to evaluate them and write one out.