I know that this film would consider Leonardo DiCaprio as the lead actor but in my mind the real star of this film (and any other film he is in) is Daniel Day-Lewis.
I catch a lot of flak from friends and strangers for being a bit critical of Leo's work. I get it, he is one of the biggest stars of his generation but I'm just not one of those people that thinks he is an incredible actor. I think he is an incredibly marketable actor in the same way that I think Keanu Reeves is marketable. However, as far as raw talent is concerned I think that Daniel Day-Lewis is in an entirely different category of skill.
Onto the story: Gangs of New York is based on fact, but all the characters in the movie are fictional. It deals with (as the name would suggest) the gangs that were struggling for power in a part of New York called "Five Points." One of the gangs is called the Natives and are lead by William "Bill the Butcher" Cutting (played by Lewis) and the other are "the Dead Rabbits who are lead by Priest Vallon (Liam Neeson.) Bill kills Vallon and declares the Dead Rabbits as being banned in the area. Vallon's son witnesses the death of his father and a tale of revenge begins.
"Amsterdam" (DiCaprio) re-emerges onto the scene 16 years later and is hiding his history of being a Vallon. He has to earn the trust of Bill the Butcher in order to infiltrate his ranks. He poses as a recruit and becomes his "right hand man" so to speak.
I will stop there before I spoil the movie.
What makes this movie great is Day-Lewis' performance mostly and also the fact that the scenes are super-high budget and directed by Martin Scorsese - so of course the production value is going to be top-notch. Most of the acting is superb and even though I don't think he is nearly as good as those around him in this movie Leo manages to pull his own weight as well.
The movie is full of action and wonderful costume design. The period accents were meticulously studied and a voice coach was brought in to do the best they could to replicate the sounds of the late 1800's. This can be particularly difficult considering that no one is really all that sure what people sounded like 150 years ago.
Overall this is a beautiful movie with a decent script and excellent directing. IT made close to 90 million dollars and won a few major awards. It was nominated for 10 Oscars, but managed to win none of them. However, at nearly 3 hours long, some would argue that it is too long. I am one of those people.
