Yeah, I hope the gravity thing changes some, because when I watched the demos it looked like it didn't add anything to the game at all. Instead it just made the tracks more interesting, but didn't actually change mechanics. When I heard about the anti-gravity thing I wanted the tracks to be more diverse. I would like to see anti-gravity gimmick to be used along with driving normal so that someone could be on the road and others on the side of a building or mountain, trying to pass them.
Also, I hope for F-Zero type speeds and level design...but we will see if we get that or not.