I have taken several MOOCs as a student as well as being a moderator on one. The most recent has been the MOOC on EMI. I quite enjoyed this but there were also some aspects that I feel less keen on.
The course was relatively small and it was possible to engage with other students and many of these were engaged and had different and interesting perspectives. We were able to make use of "collective intelligence".
It was just moderated by the two lead educators. They were very responsive and I was surprised that they were able to reply to so many comments. I assume that they must have been given time to do this. There are other courses where the moderators are much less visible.
I do not really like the "mark as complete" button at the end of each activity. This seems to imply the learning has finished but in fact, it is often important to go back to the activity (eg to respond to comments on what I had posted).
I also find the quiz items either trivial or the answers could be unreliable - I suppose this is inevitable with "objective testing" and this is the only way to cope with the size of the course.