Dance: Mr Worldly Wise Royal Opera House, London

In the risky business of new commissions, the Royal Ballet has been left badly (some would say predictably) stung this past year. Whatever the case, the company's latest acquisition - Twyla Tharp's Mr Worldly Wise - will no doubt be deemed a huge success - at least by the Royal Ballet. For not only is this a brand new, full-length three-act ballet by a big name American choreographer, it is also a major commission completed on time. But, that aside, there is very little for which to be truly grateful in this extravagant production set to a curious compilation of music by Rossini which includes the miaowing Duetto buffo di due gatti, the overture to Guillaume Tell and selections from his Peches de vieillesse.

The widely held assumption that Mr Worldly Wise would prove to be the dance event of 1995 began to crumble with alarming rapidity at the work's world premiere on Saturday evening. The Kyrie from Rossini's Petite Messe solennelle announces a prologue in which the relationship between Irek Mukhamedov's Mister Worldly-Wise and Tetsuya Kumakawa's Master Bring-the- Bag is laboriously yet sketchily established. Mukhamedov's hero figure is a clown in crisis lumbered with an apprentice who threatens to upstage him at every turn. The poignancy of the ensuing scenario in which a passionate, troubled creator eventually finds a kind of inner peace - not entirely unrelated to the progress of Rossini's own life - is frequently wrecked by slapstick humour and the over-acting / reacting of Mukhamedov and Kumakawa.

The ballet's only saving grace is to be found in its third principal role - Mistress Truth-on-Toe - created on Darcey Bussell. Bussell evolves from an intoxicating vision fleetingly pursued by Mukhamedov in Act One to become the work's guiding force - a living statement of physical and spiritual harmony and magnificence. Her dancing is at its most magical and serene in the prolonged phrases of Act Two (Tharp's best writing) where Kumakawa is out of the frame and Mukhamedov merely observes and absorbs the perfectly pitched wonders of the new land of music and motion in which he finds himself.

Ironically, while Tharp manages to mine every seam of Bussell's talent, her choreography for Mukhamedov and Kumakawa seems designed to bring out the most unappealing traits of each man's dance personality. Mukhamedov is allowed to indulge in exaggerated gesticulations which only diminish the profundity of his journey from jocular egocentricity to enlightened resolution. And Kumakawa becomes more a freaky human spinning top than a dancer.

There's an amusing divertissement for a row of performers dressed as vegetables, and Mukhamedov and Kumakawa occasionally discover some common purpose in their dancing. But it soon becomes apparent that Tharp's choreographic trickery owes as much to speed and multiplicity as to invention. Like Bussell, the quartet (Leanne Benjamin, Deborah Bull, Stuart Cassidy and William Trevitt), decorated by a busy chorus, imbues Tharp's complexity with meaning simply by inhabiting it. But their efforts fail to rescue a work that ultimately leaves you with the impression that Tharp is as clever and mannered a choreographer as Rossini was a composer.

n At the ROH, London, WC2 15, 18 and 20 Dec (0171-304 4000)