I've taken or started 5 Coursera classes and mostly had a positive experience with all of them. One I didn't get past the 1st lecture-- but the lovely thing about them being free is you can drop any time with no penalty. I didn't get all angry & self-righteous (as so many people did in the class forums), I just quit the class! My husband started a couple courses with me and dropped out halfway because he got so annoyed at the students on the forums. I have an easy solution for that. I mostly don't read the forums. They can be helpful, but if they're not, I just don't read them. (A simple, obvious solution and I don't understand why he--and all the complainypants on the class forums--don't realize that!)
My favorite was Food and Sustainability, which didn't have traditional lecture-style videos. Each week we had a few short readings, a quiz or sometimes a poll, and a video interview of an expert in a subtopic of the overall topic, like economics or food transportation or agriculture. But best of all were the creative and interactive homework assignments, such as: make a dish. Record and research where the ingredients came from and where they originated. Share your experience on the forums, and comment on 3 other people's experience.
Or: Interview 2 people (interview questions were provided). One student picked her elderly grandmother and her young nephew. I picked 2 people from different cultures.
Currently I'm taking the History of Humankind. The instructor is inspired by Jared Diamond's "Guns, Germs, and Steel". It's not a rehashing of the book, but if you've read the book that'll give you an idea of where he's going. He puts out some pretty controversial ideas but he does a good job of explaining the evidence & his rationale and he sure makes you think!
My professor friends all hate Coursera because they feel threatened that they are going to lose their jobs to MOOCs. They claim that students can't learn as well from a video as from an instructor in a class. My answer to the first concern is, "times they are a'changin'." My answer to the second is "It depends on the instructor and on the student." Their last concern is that a multiple choice test can't effectively assess knowledge. That is probably true. I don't have an answer for that. Other than that maybe they don't need to worry so much about their jobs, because they'll just be spending all their time grading tests instead of teaching the material.