I have owned the P90X series since 2008 and I have made several attempts to complete it. Due to several injuries or home renos, my progress was interrupted (once when I was in week 11 of 13). Recently, I finally finished the full 13 weeks (just before Christmas). In conjunction with a vastly improved diet, I am now in the best shape of my life. I know it sounds like a cliche but it's true.
When I started, I also hated Yoga. Now, it's merely challenging rather than downright hard. Like Tony Horton says, just stick with it and keep pressing play. Things will seem hopeless in the beginning (I felt that way). I could only do 8 pushups at a time. Now I am doing 25 per set. Stick with the program as it is designed. They knew what they were doing when they set it up. I used to get to yoga and then skip legs and back and Kenpo because I thought it was enough and I couldn't 'find' the time to complete the week and I would just reset to chest and back (Day 1 Cycle 1).
Good luck and post up your progress from time to time. Check out Beachbody.com and their discussion forums there. It might help with any questions you might have. Just don't waste your money on the supplements. Good nutrition is key though.