The goal of the Metro UI is to emphasize important content in a way that helps the user determine whether to dive into it or keep doing what they’re doing. To make all of this possible, Microsoft has introduced the concept of the hub, whose role is to concentrate all of the information onto one screen, like a dashboard. A better analogy might be the cover of a digital magazine, such as Flipboard.
Paper Prototyping, via UX Array
Read more of Panfili's thoughts at Smashing Design.