I've never actually made it through the whole 90 days of P90X, didn't really need it as I was already in pretty good shape, but I borrowed it from a friend just to check it out. I have made it through all the DVDs atleast once, and they are all pretty solid. I incorperate parts of them into my current workout regime so I definitly say go for it. Just pick the exercises you like, and mix and match them.
“To insure good health: eat lightly, breathe deeply, live moderately, cultivate cheerfulness, and maintain an interest in life.” - William Londen