Doing it right now seek. I just moved on to phase II of it and trust me it's not easy. I enjoy body workouts much more than going to the gym and lifting, I just feel better and not as tight. I would have to say that if you havent been active or go to the gym then start slowly with this workout and work you way up, cause its a bitch. I havent had a workout in which my clothes arent completely soaked in sweat. I will give you some pros and cons.
Pros
Military style work outs (not all but some, mainly push up and pull ups)
Most workouts last 1 hr (high intenisty low rest time)
Done in your own home
Limited equipment needed (might want to get a pull up tower and some free
weights*)
Get you into shape (more of a lean ripped look although you can get size just up the
weights and decrease reps)
Plenty of modification in exercises (for the ladies)
Flexibility also included (Yoga and some others, ladies kill at the Yoga)
Diet and meal program included
Cons
Listening to Tony can really get annoy after a month (haha) but there are options to listen to only cues, or you can watch the whole workout in silence (other options also)
Definitely try to get the wifey involved because you will need a partner to get you through it.
Legs are difficult, but it will be hard to add size there (if you want it) because most exercised are free
weight (lunges, one legged squats...etc) and you can only hold so much
weight
That is what I have experienced so far with the program. I really enjoy it and feel that it making me strong and reshaping my body without having to spend really more than a hour a day. Just to give you an idea, I have gone from 214 lbs to 198 lbs in about a months time (not all of that is p90x, I work as a forecaddie at golf course, but I did lose 5 lbs from p90x prior to starting work). If you have any other questions feel free to hit me up and I will be glad to help you any way that I can.
*Also I have the pull/chin up bar that the sell for 60 bucks, but I went and bought a fairly inexpensive pull/chin up bar and use that so I didnt have to screw holes in my wall. I had their's (p90x) pull up bar mounted in my old place and it worked great, I am just not allowed to put holes in the walls at my new place (I can give you more info on this if you start looking into it).