I've heard of this, and seen videos before, but it didn't look too fun or exciting... Right now, Microsoft really needs gold. Halo's over, Mass Effect 2 is ages away, Rare ain't doing anything note worthy and theres not many big titles coming out, let alone trilogies. I downloaded the demo of this and I'm way impressed.
The story sounds interesting, though I get the feeling the demo is set in some early level and not the start. A lot of mixings of Norse mythology and futuristic sci fi. I really loved how when a squadmate dies a cyborg angel swoops down to take them to Valhalla. To sum it, it feels like World Of Warcraft. In a single player Campaigne. In space.