“WALL-E” is a lot of things: a cautionary, but not preachy, tale about the environment; a sweet, but never cloying love story and a sweeping sci-fi epic with lots of robot action. But most of all, “WALL-E” is great, a film that’s just about perfectly balanced in every way, even as it creates a story about a world—our world—spectacularly out of balance. “WALL-E” is also extremely daring, a robot gauntlet thrown down as a challenge not just to other filmmakers, but to audiences as well.

Packaged and marketed as a kid’s movie, “WALL-E” is at once supremely kid-friendly and almost entirely unlike any of the kid’s movies produced in the last decade. There’s no bloated cast of celebrity voices, no riffs on last year’s pop-culture punch-lines. Instead, the first half hour of “WALL-E” plays out almost silently, save for WALL-E’s bleeps and blips, the entrancing score by Thomas Newman, and the occasional clip from “Hello, Dolly!”

Yes, that’s right, “Hello, Dolly!,” a 40-year-old Barbara Streisand musical. In the far off, yet oddly familiar looking 28th century, WALL-E (short for Waste Allocation Load Lifter-Earth Class), is the lone caretaker of a garbage strewn megalopolis. A short, squat robot that looks like Johnny 5 from “Short Circuit” crossed with a trash compactor, WALL-E’s job is to sweep up the piles of trash that have overtaken the planet. All the humans are gone and all of WALL-E’s fellow robots have long since broken. He’s the last of his kind, with only a chirpy little cockroach for a friend and a battered VHS tape of “Hello, Dolly!,” which teaches him all about romance, dancing and the humans who abandoned Earth.
 

WALL-E is lonely, but he doesn’t know it until a spaceship lands in the middle of the city and sends out a robot probe. The probe, EVE—an Extraterrestrial Vegetation Evaluator—is looking for signs of life on the wasted earth. With WALL-E’s help (and after almost blowing him up), EVE finds a small sprout, but WALL-E finds something more important: love. This first act feels like a Charlie Chaplin film run through a dystopian wringer and it’s absolutely charming in every way, from WALL-E’s slapstick courtship of EVE to his fascination with the junk-culture detritus (lawn gnomes, Rubik’s Cube, Pong) that’s piled around the Earth. It’s part love poem, part gentle critique of our wastefulness, and just a joy to watch. WALL-E and EVE, voiced by Ben Burtt and Elissa Knight, communicate sparingly and are mostly only able to say their own names. But their body language speaks volumes, from WALL-E’s expressive eyes to EVE’s sleek movements and iPod aesthetic. Writer/director Andrew Stanton, who also helmed Pixar’s “Finding Nemo,” treats his robot characters like real people, not cartoon automatons, and it’s that sort of attitude that gives “WALL-E” its heart and soul.

WALL-E and EVE end up aboard a spaceship housing the last of humanity. Rocketed to the stars by Buy n Large (the mega-corporation responsible for the wasteful consumer culture that trashed the planet in the first place), humans were only supposed to be gone a short time while Earth was cleaned up. But centuries have passed, the humans have grown bloated, dumb and lazy, and the robots controlling the ship have no desire to return to terra firma. As WALL-E and EVE try to get the plant to the ship’s captain (voiced by Jeff Garlin), absolute robot chaos ensues, with lots of machine-on-machine violence and some hilarious bits involving some spazzed out malfunctioning robots. The ship is sleekly designed, the robots are cool and Sigourney Weaver provides the voice of the ship’s computer, a nod to the movie’s science fiction roots.

It’s here that “WALL-E” gets a little sharper, but it never loses its tenderness. Fred Willard shows up for a choice cameo as the Buy n Large “global CEO,” who, in a centuries-old video recording, urges humans to “stay the course” with their wasteful ways while Earth is cleaned up. Stanton is just as harsh on the humans aboard the ship. They’re little more than feeble-minded, self-involved babies. In one scene, the ship is tilted to one side and the humans slide out of their hover chairs and pile up against a glass wall, chubby faces and butts pressed up on the glass like fleshy flower petals. It’s funny, but also gross enough to give you second thoughts about those six-gallon sodas being sold at the concession stand. But the messages found in “WALL-E”—of environmental stewardship and the emptiness and dangers of crass consumerism—never outweigh or overpower the story. Parents and kids alike can accept or reject the subtext and still be left with a genuinely funny, moving experience. If two robots can learn how to love thanks to “Hello, Dolly!,” maybe there’s hope for us human slobs to clean up our act.