I attended Startup School NYC, but would have got the same out of sitting down and watching the videos seriously. (The key is to actually do a serious viewing session instead of half heartedly watching them over microwaved lunches).
If you ask me, the primary reason to attend startup school is that you'll see a lot of "famous" people who are just names to you, and you'll begin to realize that they're human. That's a worthwhile experience if you've never done it before, but I wouldn't go into the event with grander expectations.
The hallway conversations and the networking was indeed vibrant and full of energy, but no different than any other startup event, or sxsw, or meetups, or...
I'd say that there are smaller and more focused events (Eyeo comes to mind, even though not free and much longer), that are more rewarding. Anyway, I'd probably go again if invited, mostly for FOMO (fear of missing out).