Complete Insanity

There is a new craze that is going along with the Zumba kick. It's called Insanity.
I have had so many of my friends say that they have tried this and how much it works.
I have a friend who can easily hit the gym 4 hours a day and then try Insanity and she says it even wears her out.
Another girl I talked to said she lost 4 pant sizes after she did 30mins a day for 4 weeks. I always see the infomercials but wondered if it actually worked.

By the sound of it all the push ups, jumping, high kicks, squats, etc. really works.
It's a fast pace of regular exercise broken down into small sections.