I took and take several classes, so far on coursera and edX - and I love it. Taped lectures with quizzes, weekly assignments, exam and maybe even a peer-rated project are definitely a great way to learn something! My goal always is to finish with a certificate because this gives me an idea on how well I am doing.
As a matter of fact I do not like Udacity very much. It is too playful and too unorganized compared to a lot of courses on coursera and pretty much all courses on edX. Udacity tries too hard to educate everybody by being very friendly at all times - this either leads to courses which start out all bubbly and funny and all of a sudden turn complex too suddenly - or courses that stay on that trivial level.
MOOC is awesome but what Thrun apparently doesn't get is that this concept still requires dedication and disciplin from the student. And you can design your class whatever way you like - either the student has it or s/he doesn't.
Also he is comparing apples and pears with his ratio #succesfull/#registered.
#registered of course is a marketing driven KPI and sould be as high as possible, so every time somebody clicks "Learn free" it is counted. But you have to "register" to just figure out what the course really is about and whether it is worth taking!
Also he is a business man and by switching to the new course format it is much easier for Udacity to monetarize - what a surprise. Opposed to edX and coursera, Udacity is kind of a one-man-show and he is maybe too ambitious and lacks patience (see biking with somebody else).
An article on my experience:
http://www.joyofdata.de/blog/social-network-analysis-lada-ad...