The star of Joe Roth's screwball comedy is Julia Roberts, playing fat and dowdy (well, some of the time) but it's Billy Crystal who walks away with the movie.

Not surprising either. As co-writer, with Pete Tolan, he gives himself all the best lines.

Roberts plays the meek, downtrodden sister of nicely bitchy Catherine Zeta-Jones who, with her husband John Cusack, had formed America's favourite film couple, the nation's sweethearts.

But then they separated; he went into therapy at a clinic run by Alan Arkin and she took up with a Spanish lover, played by Hank Azaria.

Since then their movies have bombed, the studio is going down the toilet and it's up to veteran publicity man Crystal to save the day.

The action takes place mostly at a media junket where Crystal has to restore the former sweethearts' popularity by persuading the attendant hacks that they are back together.

But there are complications. The film to be launched hasn't arrived yet - indeed maverick director Christopher Walken may not even have finished it - and Roberts is secretly in love with Cusack.

Plenty of scope here for sharp digs at Hollywood and, in truth, there are many funny moments.

But the parody is undermined by the fact that the film we are watching is itself clearly part of what it's satirising.

And the ending, when come-uppances are handed out, is gentle where it should be savage.

Even so there is much to enjoy, not least the performances by a very good cast.

Barry Norman