Ask HN: Your on-line education experience

On-line education seems to be growing up very fast. Starting with Khan academy, with the major players such as Stanford, MIT, Harvard jumping in, Coursera, Udacity, I expect to see a lot more emerging.

What is your experience? I'd like to group and relay good remarks into the base of the next course in development at one of the Europe's universities, but the discussion should remain open for everyones benefit.