Crysis is a decent game but far too demanding for the level of graphics it provides out of the box. Theres a mod though available that makes it look a lot closer to the "dx10 jungle fight" video they released.
http://files.filefront.com/Cuban+Ult.../fileinfo.html
Also dont bother with the mp side of things, its fun if you dont mind tools buying sniper rifles and perching cloaked at the top of hills in most maps.
For a good Mp game id reccomend team fortress 2.