Photo: Kiss Me, I''m Irish: Leonardo DiCaprio and Cameron Diaz are a lukewarm item in Martin Scorsese''s otherwise excellent Gangs of New York, which also stars Daniel Day-Lewis as a bad-ass in a black hat.

Gangs of New York is a monumental piece of filmmaking that at once tells a little-explored aspect of the making of New York City-and America-and also reminds us that Martin Scorsese is one of the most important and dynamic visual stylists to ever pick up a movie camera. The movie arrives in theatres with enough backstory about its making to warrant a movie all its own. Separating truth from fiction on this score can only be a speculative endeavor at this point. However, it does seem that the two-hour-and-40-minute epic shows signs of narrative cutbacks and character economy. Maybe this is the way Scorsese intended it, but maybe not.

All we can judge is the finished film, and as such Gangs of New York is magnificently epic, historically fascinating, and visually compelling, yet somewhat wan in terms of the depth of the characterizations and the sketchy way in which all the various strands of the movie''s Lower East Side gang wars coalesce with the city''s Draft Riots of 1863. This climax, which should have been the apotheosis of the movie''s characters and their moment in history, becomes a swirl of chaotic mayhem that lacks clarity and suitable conclusiveness.

Nevertheless, Gangs of New York is a wonderful spectacle and history lesson. The prodigious amounts of money spent on the film can be seen on the screen and the attention to historic detail is one of the film''s real triumphs. Leonardo DiCaprio is excellent as Scorsese''s leading man, Amsterdam Vallon, who returns to the sordid and dangerous Five Points section of New York in 1862 to avenge his father''s death 16 years earlier at the hands of Bill the Butcher (Daniel Day-Lewis), the barbarous leader of the Nativist gang who oppose the Irish immigration that is inundating the city. Day-Lewis casts a terrifying figure, tall and lean, a dandy with dirt and grease oozing from every pore, a savage killer with an unquenchable thirst for blood. This movie is his for the taking, although Scorsese wisely keeps Bill''s volatility in check. Still, one would like to know more about Bill the Butcher and what makes his evil heart tick. As the story''s love interest, Cameron Diaz sports a reasonable Irish brogue but has little to do and lacks the gravitas of the other actors surrounding her.

Moments such as the film''s opening set-piece-an all-out battle between the gangs, fighting hand-to-hand in the snow-or the simple act of a Bible being gulped up by the river into which it is tossed are unforgettable. Aptly, in terms of its epic sweep and subject matter, Gangs of New York reminds one most of Once Upon a Time in America, another troubled production. Scorsese works with a big tapestry here, one that includes Boss Tweed and Tammany Hall, the Civil War, Horace Greeley and more.

Gangs of New York depicts a great city born of blood and tribulation. Stick around all the way to the end of the closing credits and you''ll also remember what makes Scorsese one of the most sound and music savvy directors around. Until the director''s cut comes along one day, Gangs of New York represents the best Scorsese we''ve seen in a decade.