I set up a smart folder as an inbox in OS X's Mail client. That smart folder only shows me unread email. The traditional inbox is so cluttered and broken. Everything gets the same weighted priority in my inbox and all based on time.
That doesn't work. Categorizations (labels)seems like a great way for me to use my inbox the same way as a GTD app. That's huge for me.
I get lost in my email and over-run pretty quickly, often missing things I need to do, or revisit. I think Mailbox is on to something here. People use their inbox as a todo list already, labels just makes it easier to pull off.
Not sure I agree that everyone is winning at the same time, but the idea that one phone exists in order to solely stop the other phone from dominating is an interesting one.
It may be the case early on, but as Android grows to dominate, the whole game from Google will have to change if we assume that Google's original goal was to prevent Apple from hegemony in the mobile space.