Charlie and the Chocolate Factory (PG)

In the case of Charlie and the Chocolate Factory, it looks at first sight as if Tim Burton has an even harder job on his hands. His version is up against not only the Roald Dahl Ur-text, but the 1971 film directed by Mel Stuart.

The fondness many people have for the earlier film has always been a puzzle to me - Stuart invests the setting and story with a sticky, gloopy sweetness utterly alien to Dahl's sensibility (the secret of chocolate-making, Willy Wonka emphasises, is to keep it light and frothy). In particular, I can't bear the Oompa-Loompas: what in the book is a dignified, mysterious pygmy tribe was converted, in a fit of what was presumably taken for racial awareness, into a gang of fat little men whose faces are pancaked with primary-coloured make-up and whose hair is sprayed into rococo curlicues. I suppose nostalgia covers many sins.

Burton's version gets off to a slightly shaky start - the credits roll over footage of an assembly line on which chocolate is melted, moulded into bars, floated through the air on tiny balloons, and finally wrapped. The machinery is nicely conceived (the wrapping mechanism, in particular, has a spidery menace), but the harsh industrial atmosphere is cloyed by the unnatural, too-smooth gloss that so often comes with computer-generated imagery.

Once the credits are over, though, the camera opens out on to a grim industrial townscape of regimented back-to-backs, with Wonka's chocolate factory louring above them (Hitchcock fans may be reminded of the surreally huge ship docked at the end of a terraced street in Marnie). And at once it is clear that Burton knows exactly what Dahl had in mind; he has grasped that if Willy Wonka's chocolate factory is to seem like a child's wonderful dream, the adult world outside has to be a nightmare. The 1971 film, shot in a sugar-cake Bavaria, got this completely wrong: not to put too fine a point on it, Burton blows that version out of the water.

In terms of plot and structure, the new film sticks very close to the book. This is very sensible: I'm not, to be honest, a big fan of Dahl's, but boy, he knew how to pace a story. In short order we meet the poor but honest Charlie Bucket and his family, learn of the mysteries of Willy Wonka and the factory that works without workers, and hear news of the Golden Tickets, concealed in Wonka chocolate bars, that will allow five lucky children to tour the factory.

The impression that Burton is essentially in harmony with Dahl is confirmed as, one by one, the characters troop on. By and large, he has cast actors notable for physical extremity, or rather extremities: flapping ears, beaky noses, bulging eyes and seamed cheeks and foreheads. Charlie's dad is the wide-mouthed, irrepressibly lovable Noah Taylor; Grandpa Joe is the magnificent Irish actor David Kelly, his face at times shot to look like little more than a patchwork of wrinkles clustered around a vast proboscis; our own Liz Smith is amiably cuckoo as Grandma Georgina. Children, of course, are rarely as interesting to look at, so the nasty brats who win the Golden Tickets are lightly enhanced - obese Augustus Gloop has padding and a CGI gloss on his cheeks; spoilt Veruca Salt has an artificial and unnerving glint in her blue eyes. Among all this grotesquerie, Freddie Highmore's good-hearted Charlie is a triumph of naturalism.

It is only when we arrive at the factory that the film dares to depart from the book in any significant degree - and here is where the film's one big difficulty arises. The problem is, I think, partly one of history: in a post-Jacko era, the reclusive millionaire inviting children into his personal wonderland can never be an entirely wholesome figure, and this awareness colours Johnny Depp's Willy Wonka to a damaging degree. This Wonka is shy almost to sociopathy, and at times more infantile than the children.

For some reason, a good deal of time is given over to flashbacks in which we see how he turned to confectionery as a way of rebelling against an oppressive dentist father. At times, as he morphs from elfin otherworldliness to snapping crocodile ill-temper, Depp is delightful - is he capable of turning in a wholly duff performance? - but as a whole the performance, and the back-story, seem like a mistake.

In the context, this matters surprisingly little. The chocolate factory itself, with its chocolate rivers and edible grass and troops of trained squirrels, is superbly realised. So are the tiny Oompa-Loompas, all personified by a single actor, Deep Roy: not quite what Dahl had in mind, but a good compromise with modern, postcolonial sensibilities - in their lurid plastic jumpsuits, they also look like a gesture of goodwill towards the other film. In its combination of fidelity to its source and wacky visual ideas, Burton's take is a triumph of common sense and imagination - exactly the qualities for which we admire children.