MIT's Technology Review has one of the best survey/reviews I've seen of current MOOC programs, and also pointedly asks if they might be a temporary fad. The article opens with a fascinating comparison to the correspondence-course craze of about a hundred years ago, which made similar promises of widespread and personalized educational opportunities, and saw millions of prospective students enroll – culminating in very low outcomes and success rates, and ultimately the collapse of those programs.
American Educator magazine has a powerful “Notebook” column assessing Khan Academy, and pointing out the relatively poor quality of the lessons made available there. Quoting a profile from Time magazine, “Sal Khan... explains how he prepares each of his video lessons. He doesn't use a script. In fact, he admits, 'I don't know what I'm going to say half the time'... 'two minutes of research on Google'... is how Khan describes his own pre-lesson routine.” Note that this observation is identical to my #1 criticism of the Udacity Introduction to Statistics course, here.