The MotorStorm demo is fun and immersive. I think if they introduce more game types as rumored (1 truck vs many bikes, 1 bike vs many trucks, ...), it should hold its own against the best, especially online.
As a bonus, there are also talks about adding more character/player animation. The only thing to watch (for me) is they don't screw up the physics and the quickness in the online game. Losing details is fine by me.