> "There's no UI better than one you already know, and no UI worse than one you thought you knew but now haver to relearn."

Yeah, I guess I was overstating the case for rhetorical purposes. I don't think there's never a UI change that improves on what you already know. Once in a while a new interface comes along that's so much more efficient that it's worth retraining yourself. What I'm trying to say is that these changes are rare. I think designers tend to overestimate the benefit of a change and underestimate the power of habituation.

(P.S. thanks for catching my typo ("haver"). Fixed it.)