As for use cases, how about: it's a tablet, without the regular complexities of 'tablet mode'. It runs the same stuff as your desktop, acts, smells, barks and looks just like your desktop, and if you want to use it like a crippled toy in the style of an iPad, you're free to use the metro apps.
Let us also not be too quick to forget that Microsoft were the first to seriously meld the desktop and tablet experience. They're the only company (out of two runners, really) with a serious story in this department. Waiting with bated breath to see if Apple wholesale copies the Microsoft approach, toy-apps-as-start-button works wonderfully.