You've got to admire Matthew Vaughn's cheek. As the follow-up to his coldly slick gangster thriller Layer Cake he delivers a visually dazzling fantasy with enough romantic derring-do to hook children.

For the grown-ups there's a sardonic undertow and a virtual embarrassment of playful star cameos. Who else could lure Michelle Pfeiffer out of retirement to play a gruesome hag, cast Robert De Niro as a cross-dressing pirate, and relegate the cream of British acting and comedy talent to mere bit parts? I really wanted to love this audacious enterprise. Unfortunately, poor pacing and a clunky script (co-written by Vaughn and Jonathan Ross's wife, Jane Goldman) drag Stardust's flights of fancy too often down to earth.

In Stormhold, a magical kingdom adjacent to a prettified 19th century English village, a star has fallen to earth, in the beguiling shape of Clare Danes. Young Tristan, gawkily played by newcomer Charlie Cox, captures her to impress the vain village beauty (Sienna Miller). But Pfeiffer's crone Lamia wants to eat the star's heart to restore her own youth, beauty and power.

And for reasons too confused to explain, the fratricidal sons of Peter O'Toole's king need her to succeed the throne of Stormhold. Tristan and his prize therefore embark on a picaresque adventure that, naturally enough, turns into a love story.

The whole thing is beautifully art-directed and ceaselessly inventive, like Terry Gilliam at his most family-friendly. But the story is in desperate need of pruning and the dialogue refuses to come alive, especially in the romantic interludes.

Pfeiffer embraces the role of Lamia with relish, and like Danes offers a credible English accent. De Niro, sadly, is not very convincingly camp, and looks uncomfortable throughout. At least he gets a decent slice of screen time. O'Toole appears embalmed in his fleeting appearances, and the likes of Rupert Everett, David Walliams, and many others are underused.

Stardust is charming but, even though Vaughn has come a long way since he was Guy Ritchie's producer, it doesn't show him in full control of a director's skills.