To me ? it's the best FPS i've ever played.
Graphics are awsome , the sound is great , gameplay is just perfect , i really enjoyed playing this game , and if some tells you that it looks like Bioshock , well , i think it's more enjoyable than bioshock , you will never regret buying this game don't hesitate, you will enjoy killing human more than monsters ,
there is weapons upgrade which increase the capacity of the weapon's clip or like increasing the shot damage , just like bioshock , so it's fine .
also , you can use barrels in your peripheral to kill monsters and them up .
oh by the way , this game includes travelling to past to change the flow of the future , which it was like nice , though i hoped if they like added more travelling.
Good luck with the game , take care.