My roommate and I decided to start the P90X progam after he had purchased it and we heard success stories of others. We planned to start on a day of the week that fit both of our class schedules and other extra curricular activities.
The compilation of 12 disks is very thorough and shows you exactly what you need to do for each move. The longest of all disks is the Yoga disk, at 1hr:15min. Everything else is around the 1hr mark. The routines established by Tony Horton throughout the disks make you feel beat without beating yourself up. Because every move on every disk is what i see as "modular" you can do your own unique amount of repetitions to help yourself. He gives you guidelines that set you up for success. 8-10 reps for size 12-15 for lean muscle. And never choose a weight that you will wear you down by the last 3 reps.
Although, purchasing the pullup bar, and elastic bands are more of a burden on the cost of the program, they do help. I would recommend getting adjustable dumbbells, and they don't have to be the Bowflex SelectTech kinds, just any kind work.
The DVD's are very worth the cost. With the included diet program and fitness schedule, if you have the dertermination to go at it every day, and work your hardest. I can guarantee that success will be seen with P90X