I don't think the game is really attempting to break new ground with innovative new gameplay mechanics, but instead offer polished, satisfying and fun gameplay, of a tried and tested nature. At the very least there is some variety to be had, what with the different weapons, stealth, melee, mini side tasks and puzzles, lock picking, QTE's, collectibles or viewables, exploration etc.
More to the games focus, there seems to be a much more considered and mature level of pacing within this game than most in the genre, or games similar (barring The Last of Us), including RYSE. It's not just focused on a heavy degree of shoot shoot bang bang, or hack hack slash slash, or one adrenaline filled set piece after another, and instead has much more emphasis on grounded characters, narrative and a slower pacing with far more exposition. Some gamers will turn off to that no doubt, as it requires more patience than simple mindless shooting, but at the same time, it is likely going to be more rewarding for those after a more believable world and sense of place.