A welcome and potent title in a what will hopefully be an interesting franchise.
Since I have few complaints I'll start with them. The difficulty is rather lacking. There is always that one weakness to a patrol pattern and even if you limit yourself to a full nonlethal full stealth run, it is easy to find those weaknesses and exploit them. My other main complaint is about out of place randomness. Bone charms are randomly chosen. While their affect is pretty low, some can be quite game changing if you get them early. On the minor side, if you are going for a stealth or no kill run, it can be irritating that there is no way to ensure mid level that you haven't broken with such unknowingly, but this is a common stealth game issue (some are even worse, not telling you till the end of the game). Lastly, the abilities seem mostly to be geared towards a kill run rather than a no kill run.
Okay, now that that is all out of way, I must say, despite all that, it is still an awesome game. The story is suitable dark and interesting (although a shade predictable). I'm guessing some patching has happened as I experienced only one minor bug my whole time in the game. The powers are fun to use, and make for a lot of interesting options. The levels too give you lots of options on how to approach things. Basically, every level is like a playground for messing around.