For a single player FPS experience this game delivers. In the visuals department it's is head-and-shoulders above any other FPS currently on the market. The outdoor zones are simply stunning and if you have a high-end card supporting pixel-shaders you're in for a real treat.
You can play this game in a number of ways from run ‘n’ gun mayhem through to the pick your target carefully approach. The hardest difficulty setting made this game a challenge and allot of fun to play. Not just that, but unlike other recently released titles, it actually has a lot of content to get through. This is a BIG game by FPS standards.
Two things however stopped me from giving this game a 5 star rating. Firstly they fell into the same hole that made be disappointed with the later stages of Half-Life. They replaced intelligent, challenging opponents early on for simply filling the screen with hordes of monsters near the end.
Secondly, some of the bugs were extremely annoying. From having the NPC lady you're escorting getting perma-stuck on rocky outcroppings or under bridges, through to the game completely missing save-points.
These problems aside, I'd highly recommend this game to any FPS fan. It's a lot of fun, and fairly long to boot.