The World of Spice is a scary place - women rule and men serve only as sidekicks, villains and fall guys. It's not a bad place to visit, Ryan Gilbey says, but you wouldn't wanna live there.

There is a genuinely sweet moment in Spiceworld The Movie when the Spice Girls come face to face with a gang of waddling extraterrestrials, only to find that the aliens have made contact not to impart their superior technological wisdom, but to blag tickets for an upcoming gig. This scene will make perfect sense to anyone who has ever been addicted to pop music. If Nelson Mandela can go schoolboy-silly upon meeting the Spice Girls, then why should it be so far-fetched that alien life forms should take a detour to Earth for some cheesy Polaroids with their idols? For their young fans, the group are indivisible from the universe which they inhabit - it's inconceivable to these kids that there should be any living creature that can't whistle the Spice Girl's last single at the drop of a platform sneaker.

When one of the group fields a dumb question with the sarcastic rejoinder "Is the Pope Catholic?" it causes a media frenzy in which the Spice Girls are accused of casting aspersions on the Pontiff's validity. A 12-year- old who knows the height and weight and favourite colour of each Spice Girl but wouldn't recognise the Pope if he appeared on Blind Date won't see the joke. Which is why Spiceworld The Movie functions so effectively as a product. It makes no effort to establish that the Spice Girls rule the world - take that as read.

It's disappointing that the film never progresses beyond this initial boldness, because the script, by Kim Fuller, plays some knowing games. Sporty, Baby, Ginger, Dopey and Sneezy complain about being stereotyped, and at one point Sporty wonders if she can't change her nickname to "Sporty- but-I'm-interested-in-other-things". Yet each time we see them they are actively cultivating their respective images - Baby sucking lollipops, Sporty pumping iron. Far from being too dim to know someone is manipulating them, they exaggerate their own personas for comic effect. Even their double-decker tour bus plays up to a fan's idea of what it must be like to be a pop star, with its swings, scatter cushions and doll's house decor; though it is telling that the exterior of the bus is painted with a huge Union Jack that covers the windows, sealing the group inside a Spiceworld that is more cocoon than empire.

If the two narrative options open to a pop group are to star in a version of their own story, like Madness in Take It Or Leave It, or submerge themselves in wacky surrealism, like the Monkees in Head, then the Spice Girls have chosen to occupy the middle ground. Spiceworld The Movie is set in a tourist brochure London where the Spice Girls are preparing for their first live show, though the film's realism is two-tiered and entirely conditional. Elton John and Bob Geldof play themselves, while Meat Loaf is cast as the group's driver, a reference to his role in the 1980 film Roadie. More confusing is Elvis Costello's appearance as a barman, which is timed to coincide with a character's comment about the fickle nature of fame. The joke doesn't chime because Costello isn't in the pop dumper. Surely one of the Goss Brothers would have been a better choice, and they would certainly have appreciated the work.

The Spice Girls themselves share a flashback which suggests that they were school friends, a fabricated biographical detail, but one which makes blatant the group's decision to rewrite their own history.

Girl Power as promoted by the Spice Girls has always seemed too conveniently malleable - the group themselves award honorary Spice Girl status to any woman they come across. So it's reassuring to find them putting their movie where their mouth is. Romance is consistently squeezed out in favour of exclusively female friendship. Baby rejects a potential suitor on the grounds that her bed is already full up with cuddly toys, while Sporty just talks soccer when confronted with a half-naked Italian model. When men are involved, they are either troublesome, like the cad who deserts his pregnant girlfriend, or timid, like the wimp who is intimidated by Ginger. It's interesting that a group who are largely marketed on their looks should make a film in which their sexuality is defined by how they present themselves, rather than by how men react to them.

The characterisation is certainly crude, but there is some redeeming comic friction in the casting. Kevin Allen, who made Twin Town, turns up as a boorish Italian director; Richard E Grant, as the group's manager, has a scene in which a screenwriter pitches him an idea for a film - a reversal of Grant's own role in The Player; while Stephen Fry, last seen in the dock as Oscar Wilde, gets the film's funniest scene as a judge passing sentence on the Spice Girls for having released a song "that is by no means as kicking as your last single".

The film is generally a very scrappy piece of work, with the washed-out colours of a TV special. The timing is often dismal, but you have to marvel at the film's cold efficiency; there may be no sign of cinematic verve, but every frame pulses with sound business sense. To paraphrase the character played by Jools Holland, Spiceworld The Movie is perfect without actually being any good.