I've been doing this workout for a while now and have a few different opinions than some of the other posters. First, maybe this is nitpicking, but I think there's a big difference between getting "buff" and getting "cut". When I think of buff, I think body building and increase in body mass. When I think cut, I think chiseled and body definition. P90X is not designed to get you huge. There isn't alot weight training involved, so if you're looking to bulk up, this probably isn't the program for you. That being said, P90X will get you in the most chiseled shape of your life, if you can follow the program. A large majority of the workouts are based around pull ups, push ups and sit ups. Basic moves, but you won't find any other exercises that hit so many muscle groups at the same time. Second, I agree that with most workouts, a change in diet is the most important part - maybe 80%. I don't believe that applies to P90X. Maybe it's 50/50, but again, if you do all the workouts, you could eat McDonald's 3-4 times a week and still see results. The reason being is the program's intensity, which I found to be the most difficult and in turn, the most rewarding aspect. Yes, diet is huge, but not 80%. There is a detailed nutrional video included in the program. Third, if you aren't in some sort of shape right now, P90X will be difficult pick up right away. It's one thing to go to the gym and start bench pressing. It's another thing to start pulling/pushing your entire body weight for multiple sets. I'd strongly suggest to those who haven't seriously worked out for a while, to start doing pull ups and push ups for at least a week prior to starting the program. I'd estimate you do a total of 150-200 pull ups in the shoulder-back workout and 400-500 pushups in the chest-arm workout, depending on your initial rep count. Overall, I think it's a really, really good program. You'll work every muscle of your body while improving your cardio as well as your flexibility through the various stretching and yoga routines. You do have to realize it is a 6-7 day a week program. And for those really wanting to go crazy, there's a two-a-day workout plan. The one thing I can't comment on is the cost. I was lucky enough to have my girlfriend purchase it and use it as my own. The total package has around 8-10 DVD's, so each workout is on a separate disc. My girlfriend primarily does the yoga and cardio routines, so you do have the flexibility to create your own workout. Personally, I never liked going to the gym. I hated driving to the gym and waiting for machines or weights which were either A) Too crowded B) Too sweaty or C) Not working properly. So, with this, I didn't have to worry about any of those, and I got a great personal trainer without having to worry about scheduling or paying an additional cost. And, yeah, the guy is kind of annoying, but his enthusiasm eventually rubs off on you.