I agree with a lot of what's been said here. Like EnglishIvy mentions, I have no doubt that if I did P90x as written, I'd get great results. But like topfitmama, what happens after?? There'd pretty much be 2 basic choices, either continue to work really hard like during the rotation or end up doing much less afterward and have the physical results be brief. It's kinda like a pro athlete that retires. While they're active, they're in top shape because there are strong incentives to be that way (income, winning, endorsements, etc). When they retire, it often becomes a very different story. They just don't have the rigid workout schedule, and probably diet, they did before. They often lose muscle and gain fat. Granted, it's not always like that but I think more than not, it is. I wonder how many of the people in those P90x success pictures look that way a year or two later.
On a personal level, I've dealt with so much weight yo-yoing for decades. The last thing I want to do (again) is look a certain way only to see it last briefly. Nope...no more for me. For the record tho, I love how I look now so the incentive to formally "P90x" myself is really unnecessary. I really hate working just one (or a couple) of body parts in a workout. Kettlebells work everything.
In honor of Tony Horton tho, during my next kettlebell workout, I'll take a kettlebell off the rack and "bring it" into my hands