I finished the Darkness yesterday and I have to say that it is one of the better games on the 360. There should be more games with "possessed mafia guys with deamon arms and snake heads sticking out of their backs". I like it how you can send out the snake things and they can go everywere, like roofs and walls etc. and then devour the hearts of your enemies (who are other mob guys and the police). not for those who is not in to ulra-violent games though.
I recomend this game to anyone who is into FPS and is over 15 years. A funny bonus is that alot of the graffiti is in swedish.