A long time ago I wrote an article on rookiejournal.com regarding the battle between P90X and Starting Strength. Recently I've been watching a lot of Tony Hortons's video and decided to add a little more information on the subject.
On Muscle Confusion
A lot of people seem to hate on the so called muscle confusion principle which comes with P90X. Rippetoe himself said that "you don't want your muscles to be confused". In other words they need to get the message straight. However what really happens with P90X is not really muscle confusion. The program contains stretching, yoga, cardio and resistance training. In other words you improve your cardio, strength, flexibility and mobility. There is no muscle confusion. You just work on more aspects of your physical condition. If you are doing your regular Starting Strength/Barbell routine you are probably missing on some of those aspects. I still think that P90X is a better overall program than Starting Strength /Arnolds routine/ Greedy Joe Weider routine/ and will have much more drastic impact on your physique and lifestyle.
Before you start talking how Tony Horton, the creator of P90X, is weak and cannot squat/bench/dead as much as the Rippetoe crew keep in mind that the guy is currently 54 years old and performs better than most 20 years old. He does his own programs and they obviously work for him. How many 54 years old natural athletes do you know that have striations on their quads? Seriously? How many guys do you know at any age with striations on their quads? How many guys can do what he does at 54?
I like Tony Horton because I myself did a little P90X when I was 16 years old and that was one of my first ever training sessions. However I can see why people would hate him and would classify his attitude as annoying. I can see that.
With that being said I don't think P90X is optimal for everyone. It contains a lot of bullshit exercises - kickbacks and the original version is super core heavy. I personally prefer to do my own programs and choose exercises that don't hurt my joints. I also don't think yoga and stretching are as important as Tony Horton makes them to be. Doing the exercises, especially bodyweight, through full range of motion should improve your active flexibility which in the end of the day is what counts.
P90X sure as hell comes with annoying commercials and this shakology bullshit has to stop. I will say it once more. Supplements are nothing special and the shakology crap of Tony Horton makes no exception. Unless you go on vacation and so on you don't need crapology or any other supplement. Not even vitamins but that's another subject.
Overall I think P90X has done a lot of good to the world. No doubt about it. Huge amounts of people have improved their health thanks to it. It also affects much larger number of the population unlike the barbell programs since they are targeted mostly at young boys.
So, yes, take what you like from P90X and use it in your own program.