How good is it? Can it talk to me, learn what I know, and more importantly learn what I DON'T know? Can it use that information to help me learn various things?

Online lectures are great, but a personalized tutor could change things. If I restate back my understanding of a subject, and it clearly tells me why I'm mistaken, that's useful.

Reddit does this, kind of, today... but it's not really from an informed position. It's mostly uninformed people arguing with equally uninformed people. There are gems occasionally, but it's rare. That's why /r/depthhub was created