Film: Up

Animators often give their heroes superlative physical powers just because they can. Mr Fredricksen, the grumpy septuagenarian at the centre of Up, has by contrast a hearing aid, false teeth, a walker and a stairlift that's on the blink. It's a struggle for him to heave himself out of his armchair. He could betoken a bold break with movie stereotypes or simply be a sign that Hollywood, so long obsessed with the youth demographic, is finally wising up to the power of the grey dollar.

Up arrives in Britain on the wings of ecstatic reviews from American critics. It is an immaculately polished package, from the short film, Partly Cloudy (right), that precedes it and sets the skyward theme, to the delightful doodles that embellish the end credits. Over the last two decades the Pixar powerhouse has produced nothing but hits, from Toy Story and The Incredibles to Ratatouille and WALL-E. Up, too, will fly high in the box-office charts even though, dramatically speaking, it's broken-backed.

The start of it is stonking. A tremendously sweet and graceful opening montage condenses Mr F's entre life story into a couple of near-wordless minutes. We get to know the person behind the old-man mask of grey hair, wrinkles and big black specs. His childhood worship of a dashing explorer named Charles Muntz, whose exploits he follows in cinema newsreels, yearning to follow in his footsteps to a remote, magical valley in Venezuela. The gap-toothed little tomboy who shares his passion and blossoms into the love of his life. Their dreams and bitter disappointments and quiet, lasting contentment.

And then the trauma of bereavement, the indignities of lonely old age and the solitary confinement in the home which he has turned into a mausoleum. One day two politely uncaring nurses come to cart Mr F off to die in a gated retirement community. His response is a magnificent, spontaneous act of rebellion, uplifting in every sense.

In fact, Mr F is not without precedent. Howl's Moving Castle (left), by the great Japanese animator Hayao Miyazaki, had a young woman spending most of the story transformed into an ancient crone, and eventually embracing the experience. All of Miyazaki's work is also suffused with a passion for flying, and he has been a potent influence on the Pixar team.

Still, these are things rarely seen in mainstream family features, animated or otherwise. But then, like WALL-E before it (which was written by Pete Docter, the co-director of Up), the film loses its nerve. It slips, as perhaps it must, into something more ordinary, something designed to say, "Hey, kids, this is for you too." Still very good, make no mistake about it. But a standard action adventure nonetheless, of recognisable lineage, son of Lara Croft and grandson of Indiana Jones.

Mr F has, much to his dismay, acquired a comic sidekick, a very fat, chocolate and hot-dog munching boy scout named Russell. A junior Pangloss, the ever-enthusiastic Russell also aches to be outward bound, no matter that his main navigational skills depend on his mobile phone's GPS system. And off they waft together through the ether towards an uncharted continent ("South America! It's like America! Only South!"), where they run into magical creatures and Mr F's boyhood hero, who turns out not to be heroic at all.

There's a rare multi-coloured bird named Kevin which looks rather like a big, tropical cousin of the Road Runner, and a pack of talking hounds (in a cute narrative trick to explain why they can speak, they wear special dog-to-human translator-collars, invented by Muntz - amusingly, the scary alpha Doberman has a broken collar that distorts his voice into a silly high-pitched squawk).

There's some phantasmagorial set design, worthy of a James Bond movie, on display in the villain's lair, a cavernous airship; Muntz himself is a satisfyingly complex creation, a brilliant man driven to madness by his obsession. There is a lot of shouting and chases; and Mr F's walker comes in mighty handy on numerous occasions in assisting their escape from tight spots.

The trouble is (and this might seem like an odd observation to make of digitally animated characters) Mr Fredricksen and Russell lack screen chemistry. Their relationship is driven by cliche: they are just another brace of mismatched buddies and, if you were to predict that a close friendship would eventually form between the boy abandoned by his father and the curmudgeonly old man who was unable to have children, you would not be too wide of the mark. The bond between Mr F and his wife - though she is absent for most of the movie - is much more compelling.

But those canny Pixar people wouldn't want you to come out of Up feeling down. So the film rallies triumphantly in its closing stretches. (It is egregiously sentimental, but Pixar's achievement is to convey emotional truths with the lightest touch). Mr F spends much of the movie dragging his house behind him through the jungle - an extraordinarily resonant image, this, with shades of Werner Herzog's Fitzcarraldo. Finally, he learns to let go of his past, in the most literal sense, and feels entitled to carve out for himself a new kind of modest happiness. Though billed as a thrill-packed adventure, Up concludes that it's the smallest, most ordinary moments in life that contain the greatest adventures of all.

Up opens across Britain tomorrow.