Coffeescript is adding an abstraction level, but all the complexity of JavaScript remains, so while you write Coffeescript, you have to sort of compile it in your head. I could maybe get on board if it went one whole level of abstraction further.
I disagree; I think the more standard handling of `this` and the automagic variable scoping, constitute a significant reduction in complexity for people coming from other OO languages. Certainly for me, having more experience with Python and Ruby than Javascript.