The only "intuitive" interface is the nipple. After that it's all learned.
-- Bruce Ediger
With that said, we all know an intuitive interface when we see one. It's just too difficult to separate an enormously complex and highly context-sensitive technical process that we've learned from some kind of ideal optimum. Saying a design is "intuitive" is analogous to saying one Turing complete language is "better" than another.