(Slightly off-topic) What I feel gives Google Drive a leverage over Dropbox is the fact that it works within email. There isn't another place I need to go to share something. I just go to the place I am at and share. The people who I want to share with are already there. This works for well for both, Google's general audience as well as those SMBs that use Google mail for their work mail (read: with a domain, so it even layers a "group thing" there).