The content is good but the grading system is terrible. I could bet money that some people submit reviews without even opening the linked documents. I've gotten points taken off for missing content that was very clearly included, labeled, color-coded, and in bold. I've recieved wildly different scores on the exact same assignment from multiple people. I tested this out because one of my assignments I failed the first time for having components marked missing that were 100% there. I re-submitted the exact same assignment with no changes-- got a 100% that time. Plus if you get a poor grade you have to resubmit and HOPE someone reveiws your work, because if nobody reviews it, you just sit in limbo unable to complete the course.
The idea of these courses is fantastic, but peer-grading in this manner just encourages people to click random points and not actually provide legitimate feedback. That defeats the whole purpose of having graded written work. And if that's the way it will go, they should just eliminate peer-reviewed work in favor of the quizzes and tests, etc. Or maybe have a project that you have to submit at the end that is reviewed by a professional or something.