My Wife and I did it, starting last May.
It is an awesome program, as long as you are committed to 6 one hour workouts a week. The nutritional guide is good too - do both.
We saw big changes - even after 30 days.
Were we completely ripped after 90 days? No, but it was a big improvement over the "before" photos. We did it religiously for the first 30 days, and then prob did 5 hours a week, sometime 4, for the next 60 days.
I was formerly a runner, so now I run 10km 3 times a week, and do a couple of the one hour weight lifting DVDs a week. If it is raining, I'll do the Plyo dvd instead of running in the rain. Often on a Sat morning my wife and I will do the Kempo karate DVD - if you do it right, it is an excellent workout, fun too.....
The closer you stick to the workout and nutrition program, the closer your results will be to the ones you see in the promo. Bear in mind that many of the ones you see are after two or three rounds of P90X.
If you do as they say, you will be in the best shape of your life, cardio and strength.
Your SAC should go down, too.....
Let me know how it goes.