Koller's class is difficult, but it's a graduate-level CS class with almost all the same material as the class at Stanford. I thought she taught it well. It was rough, and I didn't make it through the whole thing the first time, but I'm back to try again.
Koller's class is difficult, but it's a graduate-level CS class
A graduate level class is not a guilt-free pass to make it "difficult". A course no matter what level, should be engaging and challenging. It need not be difficult to be an engaging course.