Chrome's initial user explosion had a lot to do with hype and newness. Or, at least, that's what you can infer as their explosive growth is now waning and users are returning to other browsers. Sites that track browsers noticed that in some areas Chrome swelled over 1% a mere day after release, an impressive feat.
That later stabled to a bit under 1%, and now has dipped down to 0.77%, almost the lowest since the browser was released. Some of the loss is being attributed to those who just wanted to test drive Chrome and are heading back to their regular browsers. More could be attributed to those who gave Chrome an honest try, but are waiting for additional functionality or bug fixing before they continue using it.
Google is already great at getting the word out for their software, so their primary goal now should be to make the browser suitable for everyday use.