You don�t have to be a 14-year-old boy to enjoy this good alien robots versus bad alien robots blockbuster, but it would help. This sci-fi sequel is a demolition derby ruled by special effects.

Transformers: Revenge of the Fallen (PG)
**
Dir: Michael Bay
With: Shia LaBeouf, Megan Fox, John Turturro

You don't have to be a 14-year-old boy to enjoy this good alien robots versus bad alien robots blockbuster, but it would help. Those with an ear for nerve-shredding explosions, an eye for nubile young ladies prone to draping themselves over motorbikes, or even just a lingering fondness for the Transformer toys of old, will think they've expired and gone to adolescent heaven.

The rest of you will have to take a chill pill and a very big headache tablet to appreciate this demolition derby of a sequel that certainly has its moments - the special effects range from awesome to magnificent - but eventually descend into a noisy grind.

Welcome to the world of Michael Bay, where anything that can't or won't run fast enough is blown to kingdom come. The director of Bad Boys and Armageddon never met a city or an antiquity he wouldn't like to see in celluloid pieces. Paris bought it in Armageddon; here it's the pyramids, while Shia LaBeouf and Megan Fox are caught in the middle of a frenetic war between the nice Autobots and the naughty Decepticons.

Bay managed something of a miracle with the first Transformers. The Hasbro toys had enjoyed a decent run on television and in video games, but the big screen had never been a place where they thrived. Bay, LaBoeuf and Fox changed that. From clunky toys past their (Optimus) prime, Transformers became a winning concept again, an entertaining blend of live action animation and human interest that appealed to all ages. Spielberg was so taken with the idea he became the movie's executive producer, a role he reprises for the sequel.

The perkiness and charm of that 2007 movie, which made $700million worldwide, is diminished here in favour of bigger, better and noisier special effects. Though impressive, the smash, bang, wallop as metal crunches unto metal isn't as endearing as watching a flesh and blood greenhorn, Sam Witwicky (LaBeouf), transform from geek to hero and get the girl (Fox) along the way.

As Transformers 2 opens, Sam still has the girl, but he's about to leave her to go to college, keen to leave the whole war of the worlds stuff behind and concentrate on his education. The discovery of a sliver of the substance that energises the Decepticons, and gives the titular bad guy "The Fallen" a chance of revenge on Earth, puts paid to such crazy notions, and soon Sam and Mikaela (Fox) are once again running for their lives from irate Swiss Army knives.

A word about Transformers here for those unfamiliar with the machines. Transformers are the wildly successful toys from Hasbro - the picture starts with the legend "in association with Hasbro" - that can change from four -wheeled cars, for instance, into upright, two-legged, man-like machines. Imagine a wreckers' yard on legs, with unlimited fire power at its disposal, or a giant metal Barbie with a seriously bad case of PMT.

Bay brings back the old familiars, Optimus Prime and Megatron among them, and unwisely adds a pair of comedy robots who are about as hilarious as Jar Jar Binks and an impacted wisdom tooth combined. It's the job of LaBeouf, Fox, and the Coen cool John Turturro (back as a former secret agent) to look convincing while acting opposite these hunks of junk. That they manage to do so is worthy of a medal in itself.

From the first Transformers, and A Guide to Recognizing Your Saints, you can see why Spielberg cast LaBeouf in Indiana Jones 4. He has the easy, movie-star-next-door charm of Tom Hanks, laced with the fearlessness of a stuntman - the ideal live action hero. Fox's assets are made obvious from the first shot of her in very short shorts, astride a motorbike. Yet from her interaction with LaBeouf, there's clearly more to the foxy Miss Fox than looks. Good luck to her in proving it in the business she's chosen.

The humans do their best, but they can't compete with the thrashing and crashing of the Transformers and Bay's dedication to blowing things up, sinking them, or otherwise creating havoc on screen (a state of affairs known affectionately in the business as Bayhem). It's a sign of how over the top he goes that a desert war - "Here come the Jordanians!" - is just one tiny part of the overall action. From east coast to west coast, from Earth to space, on land and under the sea, Bay comes out all pyrotechnics blazing.

All credit to him for his showmanship. He's unashamedly a blockbuster director who lives and breathes spectacle. Movies would be duller, and quieter, without him. Yet special effects and a wall of noise are not enough to hold the interest over two plus hours; the human factor has to be present too. Having been hot-wired once, the franchise needs some serious tinkering if it's to purr again.