Yesterday I downloaded the crysis demo and played a little bit. The graphics and physics effects look great. On my 3-year old laptop with a 1.6G centrino CPU and Raedon 9700 graphics card it runs still quite fluently.
Some tips if you're new to this game:
1. Don't waste your ammo. It's limited! However you can pick up guns when killing an enemy and take their ammos.
2. Use the jeep equipped with a machine gun, which seems to have infinite ammo. Mind your driving!
3. Press "V" key and try some options there.
Good job, Crytek.