The DMC 4 demo is now availible on X-Box Live. Just played it yesterday and have some comments.
1. In general, the camera is a big improvement over previous games. You can now turn it at will (instead of fixed angle) during a fight.
2. The Devil Bringer is pretty cool. Use it for long distance jumps, bring enemies to you, or even drag yourself to large enemies. Easily abused in battle.
3. The game looks terrific. That's all I'll say about that.
4. The boss I fought was cool. Reminds me of those Pit Lords from WC3:TFT.
5. The new roll (LB+A while moving left or right) maneuver is really useful. Saved my sorry bum on several occasions.