Early Google set themselves apart with the user experience. For example, Google Search's homepage's simplicity was astonishing at the time; a direct inverse of the bloated pages most of their competitors at the time favored (Yahoo, Alta Vista, AOL, and Dogpile were pretty bad if I remember correctly, and Ask Jeeves was somewhere in the middle. The others I don't remember as well). GMail may have not been the best technically speaking (I don't know), but from a user standpoint it was cleaner than the alternatives, who would include things like links to news stories in their inboxes.

I recommended people use Google in part because there was, at the time, less risk of them clicking on something and being confused by it. (Why is there news in my email? Where's my email? How do I search?)