Pixar's family-friendly film is an outrageously ambitious love story that pushes the art of digital animation to new heights, says Sukhdev Sandhu

Back in 1994, John Lasseter, the director of Toy Story and the genius responsible for the creation of Pixar Studios, was mulling, as he often liked to do, on how to make a character seem genuinely animated. It wasn't, he argued, that an object looks like a character, rather: "Character animation is when an object moves like it is alive, when it moves like it is thinking and all of its movements are generated by its own thought processes."

No Pixar release proves that point better than WALL·E. Directed by Andrew Stanton (Finding Nemo, 2003), it's an outrageously alive, ambitious, almost avant-garde synthesis of robot love story and ecological fable that fuses the eeriest, funniest and most memorable elements of movies as diverse as 2001: A Space Odyssey, An Inconvenient Truth and Chaplin's The Tramp.

And yet, in spite of those allusions (almost certainly knowing ones; the guys at Pixar are as much film buffs as they are techno wizards), for long stretches WALL·E looks and sounds like almost nothing you've seen before in an animated picture.

Written by Stanton and Jim Reardon, it's set 700 years in the future on an Earth abandoned by human beings. Centuries earlier, the place became so toxic with waste that a mega-corporation called Buy N Large used airliners to fly inhabitants to outer space where, gorging themselves on soda drinks, popcorn and crummy entertainment, they've degenerated into gurning fatsos barely able to move.

Meanwhile, only one of the waste-management robots Buy N Large sent to tidy up the planet survives: WALL·E (voiced by Ben Burtt - yes, Mr R2-D2), aka Waste Allocation Load Lifter Earth-Class. He's a machinic version of Will Smith's character in I Am Legend, a Robinson Crusoe figure, alone - except for a cockroach friend - on a desert island of detritus, locked into a routine of locating, compacting and stacking heaps of rubbish that create a fearful, post-manufactured landscape.

Then, one day, a fem-robot called EVE (Extraterrestrial Vegetation Evaluator, voiced by Elissa Knight) is sent to Earth by the mega-corp in order to find plant life. Despite her initial hostility, he falls in love with her and when she returns home aboard a spaceship he makes sure he's on it. Soon, they find themselves triggering a rebellion among other robots and inspiring Captain McCrea (Jeff Garlin) to return to Earth so that amends can be made for all the previous destruction.

The heart of the film, and the source of its most inspired, bewitching scenes, is its first half hour. There's no dialogue, just a series of bleeps, whirrs and squeaks - like a cross between the Smash potato robots and a soundtrack hatched up by the BBC Radiophonic Workshop. WALL·E gently motors across a parched earth full of faded street signs and collapsed buildings, heat and pollution, rendering the atmosphere dust-caked and poisonous red.

WALL·E (short for Waste Allocation Load Lifter Earth-Class) discovers a new purpose in life (besides collecting knick-knacks) when he encounters a sleek search robot named EVE Credit: Pixar / Film Stills

It's in this half hour that we see Lasseter's ideas about the relationship between movement and thought to full effect. This strange creature (a close relative of the robots in 1986's Short Circuit) chugs along, occasionally tickled by his cockroach. Then, after EVE's arrival, he alternately puts a stone on his head to protect himself from her laser and leads her to his living quarters. (The latter scene is reminiscent of Naveen Andrews's light trail for Juliette Binoche in The English Patient.) As he does so, we completely forget that we're looking at pixels and algorithms.

The confidence and skill with which Stanton's team have extended the parameters of their art form are amazing. Who else would think to make WALL·E a fan of Hello Dolly!, a videotape of which he watches and rewatches with fanatical glee? And who else - even bearing in mind that Pixar's co-founder Steve Jobs was the former CEO of Apple, the company behind the iPod - would imagine that a film's love interest could be made out of white plastic?

There's barely a scene that isn't jewelled with a sight gag, amusing conceit, or delicate detail. I laughed like a drain when WALL·E nervously hands EVE a sheet of the bubble-wrap he rescued during his rounds, only to see her pop it all in a split-second, as well as when she solves the Rubik's Cube he's offered her, at such speed that he's left baffled.

I'm focusing on the daring and bravery of the first half of the film because I must confess to feeling a little underwhelmed by its more conventional, action-led second half. The human beings are too grotesque, shorn of the idiosyncrasies that Brad Bird afforded his baddie restaurateurs in Ratatouille (2007). The ending feels pat and perfunctory. No matter: by that time WALL·E has already cast its spell.