I watched Baz Luhrmann's richly coloured, wide-screen epic Australia, a sort of antipodean, digitally animated Gone with the Wind, in the knowledge that several respected reviewers thought it was an absurdity - dim-witted, shallow, derivative and overlong. The Guardian's brainy critic Peter Bradshaw could only bring himself to award it one star, which puts it in the same dismal rank as worst-films-ever-made such as Showgirls or I Spit on Your Grave.

In truth it is nothing like as bad as that. Australia is decent family escapism and, though utterly kitsch, it moved me nearly to tears. Don't expect high art: the characters are cardboard, there are lapses in continuity, the computer-generated images sometimes look cartoonish, the love story is pure corn mush, the dialogue painfully predictable and it plays with history to boost the drama (for example, by having the Japanese invade Australia).

But even at an unwieldy 265 minutes the action was a thousand times more gripping than the last Indiana Jones film, and the romance of Nicole Kidman and Hugh Jackman packs greater emotional zing than DiCaprio and Winslet in Titanic.

The movie is narrated by Nullah, a half-Aboriginal boy played by Brandon Walters in an enchanting performance. Nullah becomes the heart of the picture. At the time the Australian authorities pursued a vile policy of forcibly taking mixed-race children, called "creamies", away from their mothers - their fathers being white Australians - and educating them in missions away from home to hide evidence of miscegenation and preserve white purity.

They became the "lost generation" and these hateful currents of racism that ran through Australian society form the backdrop to the drama. Luhrmann delineates a battle between good and evil with the invigorating clarity of an old-fashioned Western.

One day in 1939 Lady Sarah Ashley (Nicole Kidman) decides to fly to Darwin to bring back her philandering husband Maitland, who is trying to make a go of his cattle station, Faraway Downs, in Australia's northern territory. Maitland sends a cattle drover (Hugh Jackman), called only "the Drover", to pick her up from Darwin.

The journey through the outback to Faraway Downs affords an opportunity for banter between rugged individualist Drover and starched, over-dressed Lady Ashley that recalls Bogart and Hepburn in The African Queen.

They arrive to find Maitland Ashley dead - murdered by a spear apparently at the hands of an Aborigine known as King George (David Gulpilil, who played the Aboriginal boy in Nic Roeg's 1971 Walkabout). King George is Nullah's grandfather who appears to have ancestral magical powers.

We discover the real murderer is Neil Fletcher (David Wenham), a sinister villain who is the principal henchman of the rival cattle baron Lesley "King" Carney (Bryan Brown, a delight). Furthermore, Fletcher is probably Nullah's father.

As the Second World War looms, Carney wants a monopoly on the supply of meat to the army. To this end he must force Lady Ashley to sell Faraway Downs.

But she decides to build up the station herself. And unable to bear children, she grows fond of Nullah, who loses his mother when she drowns hiding from police in a water tank. The bereavement prompts Lady Ashley, in a touching scene, to sing "Over the Rainbow" to the lad. The song and film (The Wizard of Oz - pun on "Oz"?) become a recurring motif.

Lady Ashley can't drive 1,500 bulls across an arid wilderness to sell in Darwin on her own so she persuades the Drover to help. He assembles a multicultural band of drovers, including the Aboriginal womenfolk, the Chinese cook and the fat alcoholic accountant Kipling Flynn.

The breathtaking drive across the desert, with Fletcher and his moronic assistants desperately trying to obstruct them, forms the first half of the film. It recalls any number of Westerns, and the stirring soundtrack has a ring of Elmer Bernstein.

They make it to Darwin just in time. Surely the sight of Nicole Kidman will gladden the most cynical of hearts as she gallops heroically, clad now in white jodhpurs and sweat-stained linen shirt, her pearlescent skin glowing under its light coating of dirt. She and the Drover have to race King Carney's men to load their "big cheeky bulls into the big bloody metal ship" (Nullah's words).

But there's a good hour of the picture to go and in the second section, when the Japs bomb Darwin, Australia turns into a war film - lots of computer-generated bombardment with the look of Pearl Harbour.

This part of the story provides an opportunity for wrenching separations and reunions as characters who thought they were lost run towards each other open-armed.

Lady Ashley settles down at Faraway Downs with Drover (her lover) and Nullah. But the little family is soon in jeopardy again because Fletcher not only wants to seize Faraday Downs but also to do away with Nullah, the secret son who has the power to shame him.

Meanwhile, all is not well with Lady Ashley and Drover. You always feel the power resides with her, both in terms of money and mental acuity. Drover is an uncomplicated muscle-man. They fall out over Nullah's wish to perform the "walkabout" rite of passage. Drover insists Lady Ashley has no right to stop Nullah and storms off for six months' droving, apparently never to return. Before Nullah can go on any walkabout, Fletcher has him dragged off to the mission island

Luhrmann could have resolved the plot by killing any of the protagonists, or arranging for them never to be reunited. The director opts for a safe resolution while managing to spring an (unlikely) surprise. There are plenty of solemn and highbrow films in the theatres. Why not switch off your higher faculties? Australia may be hokum but it's entertaining hokum.