The Chronicles of Narnia (PG)

A Narnia as vivid as your dreams

Ho hum, eh? Another Christmas, another vast mythic spectacle, with clashing armies, magical beasts, self-doubting but essentially unambiguous good snatching victory from out-and-out evil at the last minute. I'm beginning to think tortoises have the right idea, and next year if anybody wants to paint my name on my back before I retreat into a cardboard box full of straw for the season, they'll be very welcome.

Which is not to say that Andrew Adamson's adaptation - or, more strictly, realisation - of CS Lewis's The Lion, the Witch and the Wardrobe is without astonishments, but they don't arise from the big set-pieces.

There is a scene about two-thirds of the way through when Aslan, the great lion-come-God-stand-in, is heading for a fateful midnight encounter with the White Witch, the evil enchantress who has been tyrannising the magical land of Narnia. As he pads through the dark woods, muscles rippling beneath his fur, twigs and leaves crackling under his paws, for just a split-second the illusion of weight and three-dimensional form is absolute: you know perfectly well that this is an illusion, a computer-generated image accompanied by some clever sound-design, but you can't help believing.

As with The Lord of the Rings trilogy and the Harry Potter franchise, technology has caught up so effectively with the writer's imagination that the fantasy has not had to be curtailed for the screen, only abridged. That brings advantages and drawbacks. There is the pleasure, if you have read the book, of seeing on screen something as vivid as your own dreams; on the other, there aren't many surprises in store.

For the lucky ones who haven't read Lewis's book, and are still ready to be surprised, a quick précis. At the outset of the Second World War (illustrated here with a premature and overplayed Blitz), the four Pevensie children are evacuated to the deep countryside, to live in a grand old house with the Professor and his stern housekeeper. During a game of hide and seek, the youngest child, Lucy, stumbles through the back of a wardrobe, into a magical, snowbound land, which turns out to be Narnia. Here she is befriended by a slightly camp faun, Tumnus.

Later, her initially incredulous siblings also end up there, and discover that they are destined to free the land from the tyranny of the White Witch, who has ensured that it is always winter, never Christmas. They are assisted by a host of talking beasts, of various degrees of zoological plausibility, and Aslan. There is a long chase, some fighting, a couple of sad bits, and then a happy ending.

Over the years, the book has aroused widespread alarm, because of what is seen as Lewis's over-pushy Christian proselytising, and because of his patronising attitudes towards women and non-white races. Only this week, I read one distinguished commentator suggesting both that the Christian allegory is screamingly obvious, and that in any case Aslan isn't a very good fit for Christ; while on the radio I heard another suggesting that since Lewis's notoriously dodgy racial views aren't evident in the film, they must have been "Disneyfied" out of existence.

While the social attitudes and religion do get a little overpowering in some of the later episodes of the Narnia sequence (and I'll be interested to see how Hollywood copes), this opener is thoroughly harmless. The only racial groups with grounds for complaint here are minotaurs and cyclopes, while Christianity is mixed up with a whole grab-bag of other myths, Nordic and Greco-Roman - something we're alerted to early on, by James McAvoy's flirtatious Tumnus, a twinkle in his eye suggesting he is less faun than satyr.

As for women - well, here the film may be said to rescue Lewis from himself. As Lucy, 10-year-old Georgie Henley is game and plausible, while Anna Popplewell makes Susan, the most underdrawn of the four children, very attractively sceptical and catty.

Most of all there is the White Witch: Tilda Swinton's pale, slightly inhuman beauty is not what I envisaged when I read the book, but even with her head sticking up from a series of dresses that aren't so much tailored as upholstered, she is enchanting. Under the circumstances, young Edmund's decision to betray the others to her seems like a perfectly understandable adolescent male reaction.

Parents of other adolescent males should consider that her appearance in the climactic battle-scene, all spikes and fur and flashing swords, may well inculcate a strain of sexual fantasy with which they are not comfortable.

If the girls come out of it rather well, the boys are less satisfactory. The only full-bloodedly virile character on show is Ray Winstone's cockneyfied talking beaver (another triumph of computer generated imagery, scampering and bounding and sniffing the air in a very believably beaverish manner).

But Peter Pevensie (William Moseley) is a priggish cipher of decency and bravery - here, the film follows the books in the wrong ways - and the biggest disappointment is Liam Neeson's voicing of Aslan, which has all the warmth and command of a public information film. Once he's arrived, the film's energy swiftly dissipates.

Even then, there are pleasures: that last battle, rigged up from Lewis's sketches, swooping griffins, bounding leopards and thundering centaurs. If it isn't on the same scale as the battle of Helm's Deep in The Lord of the Rings - well, be thankful.