Alrite guys, so iv just *legally*

got the whole Insanity set now.
Has anybody tried it? Anybody seen / felt improvements?
For those new to this its basically high cardio and plyometrics training on a DVD.
I did one session it was the back session and i was hurting for 2 days. Im not a small guy too, i do weights and stuff and i thought this wouldnt touch me. But the soreness felt so good.