Terrible
I am what some consider a "FPS Master," competing in the most elite FPS tournament around, and placing incredibly high in a majority. Despite this, I became so frustrated at the overwhelming difficulty of this game that I just gave up after the first couple levels. I'd like to think that it was because of advanced AI, or complex levels, but in reality, it was because of the horrible gameplay of this game. Using the mouse to both look and aim made for the most confusing interface of any shooter I've ever played, and the lack of a reload hotkey forced you to waste precious time looking to the top left corner and back after every 6 shots. The sound effects were incredibly lackluster, and despite the multiple warnings of graphic violence, none was to be seen. Bottom line: Don't bother playing...
-My two cents