I'm playing it, but so far stealth isn't very easy for me at the beginning of the game, and I know that killing too many people will get you the bad ending, which kind of sucks. I'm probably going to just say screw it, finish the game killing everyone, and then watch the good ending on You Tube. I've never been a big fan of stealth in FPS games.
But yes, it's a great title for Games with Gold.
See everyone always assumes its killing everyone that gives you a bad ending when its really high profile actions like letting alarms go off and getting into huge public swordfights. I killed everyone at Lady Boyle's party and got a low chaos ending because no one touched the alarm before rats happened upon them.
It started a bit slow for me, but I ended up quite liking it. First DLC was pretty great as well, just haven't played the second and last one as of yet...saving it for that special occasion, I guess!
That second DLC has a beautiful final level completely out of left field artistically from the rest of the game. Green is the prominent word.