The 'Killer' missing Start Screen element.
Then it hit me, why can't we have an animated background in the Start Screen, it would be an obvious influence from Android but a necessary one. Just seeing a new Bing background every day sounds very refreshing, I kind of wish the desktop app would do animated background as well. Animated tiles on top of an animated background may sound a little cluttered, but options never hurt.
Now I'm nothing special when it comes to Photoshop, so if anyone out there could slap together a render of what this would look like, that would be awesome.