It turns out that this is a great workout program. My comments for anyone considering this are directed to three considerations: equipment, time commitment, and nutrition program.
You will need dumbbells and a pull-up bar. Both are critical to being able to successfully complete the individual workouts (which are divided into Legs & Back, Chest & Arms, etc).
Buy various weights of dumbbells, and get some heavier than you think you might need. Interestingly, you will find that you are getting stronger quicker. So challenge yourself and try to max your weights to get more results. Of course, if you are going for toning, do lighter weights and more reps. On that note, you'll find that the fundamentals of strength training are continually promoted in P90X.
This is where I had the problem. This program requires daily workouts that are about an hour long (yoga is 1.5 hours). It will suck up your time. I have had to switch from evenings to early mornings, as I am usually too pooped at night and have work to do for the next day (I am an attorney and pretty much work all the time). Be prepared to stick to this - you will get results, but it is demanding.
P90X comes with a very sound and comprehensive diet plan. I have really never understood what nutrition can add to a exercise plan. Do not starve yourself - eat what they tell you, because you will need the energy to do the strength training, trust me!
I have lost weight eating more than I have in the past year. I was in training for a 1/2 marathon from August to February, and ate like a finicky bird. Now, I eat all day long and have dropped about 6 pounds.
What is more fascinating (and amazing) is that I am becoming more "shredded." For the first time in my life I am showing ab muscles. I still have an annoying "pooch" in the very front, but I can see the muskles (as Popeye would say) around the sides under the rib area. I attribute this in part to the diet, and in part to the AB Ripper X component of P90X.
By the way, get a protein drink and/or the P90X Recovery Drink. Their drink is awesome (tastes like the old Orange Julius that were in the malls in the 70's and 80's). Sports nutritionists have concluded that feeding your muscles within an hour after a workout is critical to muscle recovery and development, so DO NOT SKIP THIS! You wont gain weight (my wife refuses to believe this)!! I added a NOS brand protein drink in the mornings (especially the morning following weights). NOS is micro-protein that is absorbed super fast, and has little carbs that can make you fat.
In short, I am very pleased with this program. I have about a month remaining, and then I will train for 8 weeks for some summer sprint tris. The neat thing about P90X is that, as it has 12 different components, you can mix n' match the various workouts depending on your goals. They have several modified programs in the P90X manual, and I have noticed online that people are coming up with programs and posting them for everyone's use.
This is a great program, and, to quote my new hero Tony Horton, "I highly recommend it."