I took Dan Ariely's course through
https://www.coursera.org/course/behavioralecon . I didn't get anything out of it, really, outside of what I got from reading his books (free from the library). His video lectures were very engaging and well done, but I preferred reading his books with the same info.
The grading was super easy (online multiple choice quizzes and tests and essays for the "distinction certificate" that were graded by the other students). I finished the course with a distinction certificate and a 99% in the course, and I stopped putting more than about an hour a week into it after about the first 2 weeks. Really, I found the testing/grading/feedback very disappointing.
Obviously, other MOOC courses may be very different, but I think that a course where an instructor is paid per student (eg, a Master's class that your work pays for) will probably be very different from a MOOC (eg, actually having your essays graded by an expert).
In the interest of full disclosure, I'm a college prof myself (so there may be some bias there), but don't teach any online courses, and I was really excited about the MOOC possibility.