It may be that many found the course too difficult, but I am certain it was comments on the quiz that he had just given that stated it was too easy that highly offended him (how many said that he never really said, but at least 2 or 3 apparently did), and was the source of his parting quote that was something along these lines (regarding the take home exam): "Even experienced mathematicians will find this non-trivial" The reason for such a difficult take home exam doesn't really make sense unless it was in response to that (By the way, I just found the exam a few weeks ago; I had kept it but didn't know where it was; I almost feel like putting it up on the web someplace). It certainly doesn't address criticisms that the course was too difficult; he only intensified that enormously by that exam.