Got this from Redbox free for a day (and ended up keeping it for a few). It got great reviews but I was still hesitant, so when I got the free promo code, I figured that was the best way to really find out.
This is a first person stealth game, and a very nice looking one at that. I read two of reviews of it and both had the same comment - for a game that would prefer you not to kill anyone, why do they provide you with so many ways to kill? You constantly have a blade in your hand and while you may put it away, as soon as you perform an action, out it comes. Presumably it is there for defense, because you can defend and then use non-lethal measures. Having it there though means you will eventually strike someone.
The story is pretty good and there is a LOT of exploring and interesting side missions that play to your benefit. As mentioned, for all of your primary tasks as an assassin, you can either perform the task directly or try to find a non-lethal method to achieve the goal. The side missions tend to either directly or indirectly aid you in the non-lethal aspect.
If you've ever played a stealth game, the fundamentals of this one aren't much different, however they really worked in how your choice to kill or not affects the cities. The more you kill, the more enemies and difficulty you encounter and the "darker" the cities are. The repercussions of your actions are immediately visible in things that NPCs say and how they react to you, as well as the comments by the government PA system. If you play through multiple times and choose different actions, this is quite evident and this adds an interesting layer to the game.
I wasn't able to finish it because I kept trying different things (meaning I was having fun), but I will be picking this one up. It is very fun. Recommended.