i just started P90x but am doing it modified. Staying on my very fatty semi-low carb WOE (50-100g) and doing the exercises about 4x a week (so i guess for me its gonna be P150x for me. I also walk a lot and have always had a pretty healthy metabolism.

the exercises are hard, especially for a woman with no upper body strength, which is precisely why i want to do it. so far I like it, and its a very cheap way to get in shape. the trainer guy is not grating on me yet, but i feel he will be.

btw- i dont use a pull up bar, all you need is bands. they show you how to use them for modified versions of the exercises.