I enrolled in the computer vision course and was very disappointed with Coursera.
There were several problems where I mention the 3 main ones:
1) The content of classes very shallow;
2) An almost complete lack of relation between the contents of the classes and the tests; and finally,
3) No pedagogical support, or communication channel, e-mail, chat, absolutely nothing.
Summary of my impression: I felt myself studying alone, reading a vague material, and experiencing tests that could not be solved based on class.
It is a 5-week course, and I noticed from the drastic drop in participation in the forums that the students, like me, are giving up after the second week.