Very good FPS. At the beginning the game doesn't make a great impression because the "rythm" is maybe a little slow, but then it developes very well and the game becomes very challenging and enjoyable. You will always want to know what's gonna be next, till the end of the game.
I really liked the music of the game and the graphic is very good too. The only "weak" point is that the AI is not always perfect, but that's not a very big problem.