If it's forced enthusiasm, I definitely get annoyed. Like they're this rainbow, happy-colored, no-one-is-supposed-be-this-happy type of person who denies reality in favor of enthusiasm. That really annoys me because it is so forced and fake. If the person is naturally enthusiastic, let's-get-this-done type of person, I don't mind, and I do find it attractive. I myself, like other IxFPs it seems, have some trouble getting excited over things. I prefer to show it, though, than speak it when I do, as I think more people ought to do. (I think that's where my annoyance with over-enthusiastic people comes in.)