My issue with p90x is time, the workouts are too long for me. An hour of full-body strength training would be realistic, but you don't need to work on 2 muscle groups for so long. (And do you really need to work for an hour on your core? I think not!) So I cut them down and I still get results - they have a tendency to do a series of exercises and then repeat that series a second time, before moving on to the next series. I usually just complete the 1st set then skip to the next series. This cuts the workout in half.
Not sure how advanced you are, but I definitely prefer Plyometrics over Cardio or Kenpo. I also customize the schedule to meet my needs - I like doing other workouts besides p90x.
I got this idea after reading about other people doing it - http://fitnesswithjessica.blogspot.com/201
But if you want to stick strictly to the program, more power to you!