On the positive side, the benefits are substantial. 1. Democratized access to the world's top educators, 2. Low cost distribution of education.
On the negative side, the MOOCs are kind of the large classroom problem taken to the extreme. It's generally agreed that a classroom with more students per teacher is not as good as a lower student/teacher ratio.
But to critique my own negativity, the people working on MOOCs are smart and motivated. It's a bit naive to think that the current MOOC is as good as they will ever get. Clearly, these are early stage products that have substantial evolution and improvement in their future.
The one area in open education that needs to improve is around content licensing. If you look at most open educational content, the licenses are restricted open source (GPL like) and note unrestricted open source (MIT/BSD/Apache like). I fail to understand how making the content unrestricted would not benefit everyone.