Their is violence in the movie but IMHO it is not over the top but is part of telling the story. They had a show on the history channel last night that did a good job of telling the history of the 5 points of NY and how things were in that time era.
I also didnt think the moive was that bloody. I have seen movies where they used way too much blood but i think in this moive it was part of the story and wasnt over done or done intentionly to get a re-action out of people!!!