I liked it quite a lot!
What i liked: story, missions, weapons, difficulty of the game, graphics, music/sound, movements. This game has like everything a stealth game needs. The enemies are intelligent enough, they notice you when you whistle or make some noise, even if they soon stop searching for you if you become quiet. One of the things i liked most, was sneaking behind enemies' back and "grabbing" them, knocking them or interrogating them(pretty helpful sometimes). The weapons are good enough, just good and stealthy :) You can take down the light for a few seconds, enough for you to sneak between some enemies in a very lighted area. You can also kick down enemies by "shocking them" or killing them with gas.
The hacking system is very reliable and nice. You can hack computers for data, as well as doors' security systems.
What i didn't like: the game was kinda short. I expected a longer story and game, but it ended fast :(
In conclusion, a game worth playing. One of my fav games ever.
"Nothing but ghosts and shadows."