I would suspect that Dropbox has a pretty fanatic group of fans out there. I'm one: Dropbox saved my ass when Boot Camp wrecked my hard drive. 7 years of documents were all saved, even though I'd deleted them from Dropbox previously. That's an
incredible service. I recommend it to everybody who needs a good way to store stuff online, or share stuff.
Google isn't omnipotent. Orkut was a terrible social network because they just didn't get what to do. I'd guess same goes with that animated world they made that just recently closed. While they're powerful, it's really hard to beat out a truly stellar product, and Dropbox is one of the best I've seen.