I used the service to get through Calc 2 as an undergrad. I liked it so much (went from a C+ to A student in math) that I went to work there the next summer!
The majority of class was spent with him in the front of the room responding to questions or comments about the assignment. He was really gracious and took the time to respond to what might have seemed like bad questions and somehow use them as a springboard to further the discussion.
He would also usually throw out book, movie, or music recommendations that popped into his mind during the course of the class that was related to the topic.
His passion for history and ability to engage the students was what made him an excellent professor.
On another note, one of the biggest, and most baffling, complaints I heard from friends who went to a large local state university was foreign lecturers whose English was so poor they couldn't understand what was being said.
There are some schools trying it out, using Khan Academy and other resources. I've visited a few and it's neat to see. I've also been doing that model in the weekend workshops I teach, and see definite benefits. No more having to rush the students that need more time or bore the students that got it quickly.
Where are you based, if you don't mind me asking. I'd be interested in volunteering at programming workshops in/around San Francisco.