I didn't have high hopes for this game after Conviction but when i finished the first level i thought to myself: "they did it...".
Stealth system is so deep,basically they implemented every mechanic that you need in a stealth game.Lethal and non-lethal takedowns,hiding in shadows,cover mechanics,cover takedowns,aerial takedowns,human shield option,you can move bodies(it was fun to throw them around because the physics are great) and of course,huge variety of silenced weapons that you can upgrade.
Also movement(walking,running and sprinting) is almost spotless with great animations and controls.
Play it on Perfectionist difficulty because that's where the game shines.AI is smart and they react on almost everything very quickly.You can tag on perfectionist but only 3 enemies. Sometimes you need to use it because you are facing a group and everything is in timing.Shooting mechanics are good and there is no better feeling than when you take down an enemy with a headshot,blood cloud appears,he falls and you start to admire the blood splatter on the wall. xD
Checkpoint system is being used and it feels more satisfying to "clean" the area in one go especially in BONUS/SIDE Missions (yeah BONUS/SIDE Missions that you get from your crew members).
If you enjoy stealth you don't want to miss this.