This game is satisfying in so many ways...
The only flaw seems to be vehicles (especially) loose graphics(?) when running, or when not focused in on. Its very minor and does not really effect anything.
Story - The end of civilization, huge monster aliens, individual characters that have their own micro-story that makes the whole "earth being taken over" plot personal. It makes you want to fight that much harder for them. Which is why a real soldier fights. For the guy next to him.
The real genius of the whole game is. Even if the graphics were tone down and the storyline did not exist. This game would still be great. Its the game play that makes this game unstoppable. NONSTOP ACTION, lots of blood and gore.