It is amazing. I am getting better results with 7 minutes a day than when I was training for 3 hours a week. It's like a caffeine boost in the morning, and lasts for at least 12 hours.
No offense, but I question whether you were working out properly previously.
I have been doing martial arts for about 6 years with different teachers. I think they have taught me how to work out properly. What I've seen is that exercising gets you diminished benefits as training tome increases. For now, 7 minutes a day is just fine.