There was a review which specifically mentioned a Holocaust course, which was described as being taught by renowned professors in the field. As it turned out, the videos used in the course had been created years before--it was not new material--and they got intern TAs to create the questions and exams and other course material and participate on the forum for the course. The actual professors had nothing to do with the course at all. They didn't advise on what material to use or create new material or have any hand in the course other than having lectures taped years ago.

Also, since it's a peer graded system, it's really difficult to get a gauge on how well you're doing unless they do multiple choice exams/tests. The person who is grading your paper could be a high school student or someone with a degree in the subject, you nver know. Which, while certainly something that can be used in a course, aren't always the best for figuring out how much you really understand material.