Directed by Martin Scorsese, starring Leonardo DiCaprio, Daniel Day-Lewis, Cameron Diaz, Jim Broadbent, John C. Reilly, Henry Thomas, Brendan Gleeson and Liam Neeson.

With a gestation period of over 25 years, and a production which was allegedly plagued by a spiralling budget, rows between director and producer as well as a script that was tossed between four different writers, 'Gangs of New York' is a big deal in every sense of the term. Put simply, it's a colossus.

The film's credits immediately reflect the lofty aspirations of the piece. Scorsese, Weinstein, Zaillian, Lonergan, DiCaprio, Diaz… names which will be recognisable to even the most casual of movie buffs. And then there is the name of Day-Lewis, but more of that later.

New York, 1846. The city is a cesspit of crime, squalor, deprivation, violence and relentless misery. Into this festering mess pours thousands of Irish immigrants on an almost daily basis, leading to a battle for territorial control of the tenement Five Points district between rival gangs of Irish and the so-called 'Nativists'.

The film opens with a pivotal battle between the Irish 'Dead Rabbits' and a gang of Nativists led by the barbaric Bill 'The Butcher' Cutting (Day-Lewis). The Butcher kills head Rabbit 'Priest' Vallon (Neeson), a key victory in his journey to becoming the criminal leader of the Five Points.

Cut to 16 years later when the only thing that's changed in the Five Points is the date. Lawless crime is exacerbated by unease at the government's Civil War conscription methods, while The Butcher now dominates the landscape with the help of the infamously corrupt politician, Boss Tweed (Broadbent). Having witnessed the brutal slaying of his father through a child's eyes all those years before, Amsterdam Vallon (DiCaprio) - who has spent the last decade and a half in institutional care - returns to the Five Points eager to avenge his father's death.

Having established the film's dynamic with a blistering opening hour, 'Gangs of New York' loses its momentum halfway and never fully recovers. The blame must be shared. The script - which producer Harvey Weinstein claims was passed back and forth between four different writers (only three are credited) - is only fitfully engaging and often lags at crucial junctures.

The actual narrative of the piece is also diluted, it would seem, to ensure smoke is coming out of cinema cash tills. With DiCaprio signed on to play Amsterdam Vallon, it's hardly surprising that a leading female would join him to plug the subplot marked 'love'. That particular role goes to Cameron Diaz, whose problem isn't so much one of performance, but rather of necessity. And even if we can accept the need for a love interest for the heroic lead, the love story here makes illogical leaps towards longevity.

As for DiCaprio, it's hard to escape the feeling that he was simply miscast. Having swapped admirable acting ('What's Eating Gilbert Grape?) for maudlin movie stardom ('Titanic'), it seems Leo is now chosen more for his commercial appeal than his talent. Apart from the fact that his accent is all over the place (having lived in America most of his life why does his character speak in ridiculous leprechaun tones?) he lacks the physical presence which the character most needs. In the end, he is simply devoured by Daniel Day-Lewis.

Having being tempted out of retirement by the prospect of working with Scorsese again, Day-Lewis is the film's lasting legacy. His feral, ferocious and utterly pulverising performance as Bill The Butcher annihilates everything else. Perhaps there is an argument that he sometimes borders on villain parody, but nobody can deny that his turn is a memorable tour-de-force.

One surprisingly disappointing aspect of the film is the battle scenes. As you would expect from Scorsese there are some supremely stylish moments, but one is left curiously devoid of any lasting impact. This may be down to overly flashy editing, with the action chopping and changing with unnecessary alacrity. After 'Braveheart' and 'Gladiator', there is nothing particularly exciting here.

Yet for all its flaws, 'Gangs of New York' is still a film that demands to be seen. As a chronicle of the dark birth of America's unofficial capital, its exposition is ultimately unsatisfying, but at least it touches on events that have hitherto been neglected by moviemakers.

And welcome as it is to see Scorsese (somewhat) back in the groove, it's even more welcome to see Day-Lewis burning up the screen once again after a five-year absence. His chances of a second Oscar? 'Put your money on now', says Harvey Weinstein. It's hard to argue.

Tom Grealis