BMW Driving School

Is the BMW driving school (the M school) a good driving school? It looks to me like it may be a school to learn to drive fast cars, not drive cars fast. Right now I'm decently quick, I do alright when I go karting here in Charlotte and I can heel-toe just fine, and the cars in the garage here at home are faster than the cars the BMW school offers anyways. I just want to make sure if I go to the driving school that I will actually gain a good deal of driving ability, so I'm wondering if anyone here has been there and their thoughts.

Thanks, Chris