Unreal 2 really is a blast. Like most shooters it has a fixed story and you always just have one way to move through the game. The story is fun - but a bit foreseeable.
Great feature (in my point of view) is that you have some missions with a team. You give them orders where they have to stay to defend an area. You need to decide on your own where to put the guy with the big guns, or where to deploy your comrad with the sniper. that gives some of the missions a tactical touch.
All in all a great game!