The individual lectures are well-structured, clear and the lecturers put the media to good use. The course as a whole, however, is very heterogeneous. Having a separate speaker for each topic is nice because you get to attend a lecture from someone who is high specialized in the topic she is lecturing about. However, if the coordination between the speaker is not well managed it leads to a lot of heterogeneity, which, again, is the case here (different speakers don't expect the same level of prior knowledge from their students, they cover some of the same material, they don't connect what they have said to what the other speakers have said...)
I would add that it is irritating to follow a course where the speakers just assume that the attendees are all Americans. Wake up! There are people from all over the world on Coursera! Moreover, I don't mind following a course on Chemicals and Health in the US but it should be clearly stated in the info on the course.