It's useful for tablets, but it's by no means a tablet thing. It's more like a...a command center. I was looking for a new car recently, and was wishing that AutoTrader had coded up a Live Tile that would update in real time with new listings that matched my search criteria. It would have saved me a bunch of wasted time refreshing their site only to find that there's nothing new. It's that sort of stuff that I'm looking forward to having.
It won't be to everyone's taste, certes, but its usefulness doesn't depend on having a certain type of screen.