I took the first iteration of Startup School, and while the lectures were outstanding, the weekly calls with the mentor and classmates didn't really help.

I guess it depends on what mentor you get. I've heard of people having excellent mentors, and others that didn't even show up half the time.

But it probably also depends on your experience level as an entrepreneur. If you are just starting out with your first venture, then it can definitely be helpful if your mentor doesn't suck. If you are experienced or your mentor sucks, it's a waste of time.