I agree that it's a noun; but, it certainly could be a verb. Interestingly, if it were a verb, its pronunciation would change from long 'i' to short (how many other words do this? -- a challenge to everyone). As to its ambiguity, I disagree with those who sound disapproving; the ambiguity may have been intentional, and it adds interest to a statement which is otherwise very commonplace almost to the point of being banal.