Gimmick. Just work your butt off and when something gets easy make it harder...They bring up a lot of "muscle confusion" in their program. Its BS. Basically, if you want to save yourself some money but get the "P90X" workout, do this: Set a number of reps and weight (whichever applies) to a certain exercise. Make it fairly difficult. Once it starts getting easy after many workouts, even a little bit easier, make the exercise more difficult. Increase the weight, the reps, or just take your time with it more. (Lifting weights slowly is a lot harder)
I'm only 16, but I've become a bit of a fitness expert, lol.
I did this for 2 weeks and it worked GREAT. I didn't stick to the program schedule and was just using a used set of the DVDs with no special diet or equipment. I've also used Chalean and Insanity which both worked well, too. I agree in a way that the programs can be gimmicky, but I think they ARE effective. Also, it's REALLY hard to stick to and create a really intense workout routine of your own. Especially in the busy/stressful lives many of us lead. I can't even think straight by the time I'm out of work and would NEVER be able to think of my own exercises in that time just because my brain is fried for the day. I can focus all my energy into the muscles being used and the effort I'm putting in if someone else is calling the shots ;)
My daughter does it. Has for several months, but she is somewhat of a fitness addict. SHe has now gone to the newer "insanity" workout, which she says is much much harder. She does these on her "off days" in rotation with her gym workout and running a minimum of 25 miles a week.