But to properly understand the crux of Boyle's biggest hit, we need to return to the film itself - specifically the final sequence before the closing credits. After nearly two hours of scintillating high drama - conveyed with great storytelling technique and visual panache - the film suddenly switches gears and lands in Bollywood territory. The leading cast members (the adult leads with hundreds of extras, and separate scenes for the child actors) embark on a fantastic song-and-dance routine on the platforms of Mumbai's Chhatrapati Shivaji railway terminus. It's at once uplifting and aberrant to (western) filmmaking conventions - which could best describe Slumdog Millionaire, a film oozing manic energy and blistering imagination.

Much has been said about the film's feel-good ethos. Indeed, one can see a happy ending way before it comes. The film follows Jamal's (Dev Patel) account of his journey from the Mumbai slums to being just a few questions away from the top prize at the Indian version of Who Wants to be a Millionaire. We witness the way the boy (played as a child by Ayush Khedekar) weathers abject poverty, race riots, malevolent child-beggar handlers, exploitative manual labour and the repeated betrayals of his unscrupulous brother Salim (played as a child by Azharuddin Ismail and Madhur Mittal as an adult) on his way to sit across from narcissistic Millionaire host Prem Kumar (Anil Kapoor, above right, with Patel).

But it's how the story is told that makes Slumdog a thrilling cinematic spectacle. The novel on which the story is based, Vikas Swarup's Q&A, certainly had much for screenwriter Simon Beaufoy to appropriate, but Boyle's deftness with edgy imagery - in collaboration with cinematographer Anthony Dod Mantle - is what makes the film tick. Jamal's numerous flashbacks to crucial episodes in his life are rendered vividly on screen. They are intertwined with his attempt to locate childhood friend-turned-sweetheart Latika (played by Rubiana Ali as a child, and Freida Pinto as an adult).

It's true those episodes may reveal a scattergun image of India, but one can easily sense Boyle's hearty celebrations of the many traits of Indian popular culture as well. For example, he focuses on the widespread public fascination with cinema (as shown in the desperate lengths young Jamal goes to for Amitabh Bachchan's autograph) and, of course, television shows such as Who Wants to be a Millionaire.

Detractors take umbrage over the film's exotic portrayal of the country's underclass. But it's actually the country's ruling classes and privileged elite who are under attack here, as seen in the way Jamal is arrested and abused by the police for allegedly cheating on the programme and mocked as a chai wallah by the English-speaking Kumar.

Bar the odd concessions Boyle makes for the international market - such as abruptly switching from Hindi to English in the second half of the film - Slumdog chooses to avoid falling for the option of giving India a lazy, exotic makeover. Instead, it's a film that radiates empathy, but also makes sharp points about the country's progress in this modern, globalised age. It suggests class antagonism is a concern for society and a root of its poverty.

For this alone, Slumdog has atoned for some of its flaws and risen above the standard of many films, offering a rags-to-riches story beyond western-centric terrain.

Slumdog Millionaire opens today