THE films of Hollywood director Michael Bay have the subtlety of a thermonuclear explosion. And in Transformers he has finally found the subject material to match the scale of his ambition: 30ft, bulletblasting, shape-shifting, alien robots. From Bay's point of view, human beings never created enough of a rumpus. By working with robots he has now created a summer blockbuster that is shining new and a lot of fun. It's so visually inventive watching it makes you feel like a kid again. Bay might have earned our forgiveness for Pearl Harbour.

Transformers, a toy franchise-toscreen story about warring robots on planet earth, is a preposterous concept. The human characters in the story are thinner than sheet metal; its story as tatty as a holey bucket: good and evil alien robots come to earth to get their metal mitts on a giant cube hidden in the Arctic, while teenager Sam Witwicky (Shia LaBeouf) gets caught in the middle. The bad guys . . . Decepticons led by Megatron . . .want it to power their takeover of planet earth. The Autobots, led by Optimus Prime, plan to stop them.

(The robots can disguise themselves as vehicles, and the film begins to look like a General Motors advertisement for boy racers; Bay's camera slavers over the buffed surfaces like an auto fetishist).

But the director also behaves like a child savant . . . albeit a child with attention deficit disorder and $150m in toys at his disposal. The film's brainlessness is forgotten in the aftershock of the blast. Somehow, not only do these robots look real, but they are made to transform and fight like human Capoeira dancers. Michael Bay has bestowed these hulking metallic machines with grace. That in itself would be meaningless unless the film too was up to scratch, which it is: it's thick with fastpaced action and peppered with good humour.

LaBeouf 's teenager Sam is known to the robots as Ladiesman 217. He's actually a skinny nerd trying to auction his explorer grandfather's glasses on eBay. But, unknown to him, embedded in the glasses is a map that leads to the cube. His first car is actually a Transformer in disguise which communicates by dialling tunes on the radio. LaBeouf makes the best of it with a fast-talking shtick . . . like a young Will Smith oozing charm and laughs. But it is apparent soon enough that the director is bored by humans.

There is a lot of hokum from Optimus Prime about humans deserving to be saved. He talks like a robotic Dan LaFontaine, the man with that sonorous voice in movie trailers.

But the laughs keep coming.

Only Michael Bay could get away with a scene in which a giant robot urinates petrol onto the head of a government agent (John Turturro in pantomime mode). There is also much amusement in watching a number of enormous Autobots trying to hide from Sam's parents in their back yard.

Taking cues from Spielberg's Saving Private Ryan, Bay takes us into the centre of the action. At one point, we pause to experience the disorientation of an explosion.

For about five seconds, the sound and screen goes woozy. And then wham! We're alive again. Bay's camera follows the trajectory of a pair of brawling robots as they smash through a skyscraper and out the other side. He throws rubble about like rain.

Amusingly, our attention is repeatedly turned back around to the faces of human spectators as they watch the Transformers in action. "Oh my God, " they repeat over, with their eyeballs hanging out. It's a manipulative old technique of a director who is insecure about how his audience will react: show characters looking stunned and your audience will feel stunned too. But Bay should have no fear . . . it would take a cynical robot not to be awed by these creations.

The Simpsons Movie (David Silverman): Dan Castellaneta, Julie Kavner, Nancy Cartwright, Yeardley Smith, Hank Azaria, Harry Shearer, Albert Brooks
Running time: 87 minutes.
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IT'S yellow, ageless despite being 20 years old, and it's up there on the big screen, looking exactly how you would imagine it. Yes, it's Bart Simpson's penis.

The full-frontal joke springs from a naked skateboarding scene through Springfield in which Bart is finally defigged after various imaginative ways of covering him up. The skit says: 'we dare to do in film what we can't do on TV'.

But while The Simpsons Movie sustains 87 minutes of hilarity, lampooning everything from environmental disaster to an ineffectual US presidency, it is no more funny than a great episode from the series' early heyday. So it's a return to form for a TV show that has been in the doldrums, rather than a cinematic big leap.

But the anticipated moment of devastating comedic impact never arrives.

It's easy to forget what a revelation The Simpsons was when it first emerged: a family programme which pulled no punches. It lacerated all sides of American culture; it was cynical and post-modern, but had a soft spot for family values. And indeed, that is at heart what the film, 18 years in the making, is about . . . a reuniting of the Simpsons family after an ordeal which involves a saving-the-day action movie storyline.

It trawls through their dysfunction with slapstick, one-liners and satirical glee, and Homer is forced to endure a long night of the soul . . .and a lot of violence too. But not after a lot of self-referential skits.

"I can't believe we're paying to see something we get on TV for free, " says Homer looking out of the cinema screen. "Everyone in this theatre is a sucker."

It's difficult to discuss the film without spoiling the jokes. (And the film is gut-bursting with jokes: it would be wise to sit through the final credits, where Maggie has something interesting to say).

Bart's anti-social tendencies are blamed on Homer for not taking an interest in his son; Bart finds a surrogate father in Ned Flanders; Homer adopts a pig and Lisa falls in love with an Irish boy called Colin who is "not Bono's son".

Lisa is also campaigning to save Lake Springfield which has turned radioactive green. She resorts to an Al Gore-style environmental campaign called 'An Irritating Truth' and the town finally cleans up its act.

But then Homer causes an environmental catastrophe on an epic scale. Springfield's future is under threat from the American government which is taking advice from the chief of the Environmental Protection Agency, a man of extremely dubious motives voiced by comedian Albert Brooks. Worse still, Homer finds himself being abandoned by Marge and the kids. Not only does Homer have to save the day, but he has to win his family back too.

One of the tasks facing creator Matt Groening and director David (Monsters Inc) Silverman was to make the Simpson characters worthy of a feature-length film. In this they succeed: there is more emotion, sympathy and more heart.

But there are also periods when the film feels strained. The barbs are unrelenting though: The Fox network gets shafted; Iraq policy is ridiculed; The Patriot Act is mercilessly abused and Arnold Schwarzenegger has become a pathetic US president, with the inadequacy of a George W Bush.

Despite this, the film doesn't do a demolition job on popular culture, which I was hoping for. And its irreverence falls short of genuine subversion. It's very funny ha ha, but a little too much funny familiar.