Many will wonder why the Royal Opera is presenting La Finta Giardiniera. Mozart wrote it in 1775 when he was 18. It's no masterpiece, and its appearance seems perverse at a time when major scores such as Idomeneo and Die Entführung aus dem Serial are absent from the company's repertoire.

The most frequently voiced argument in its favour is that it represents Mozart's first plunge into the emotionally ambivalent territory between comedy and tragedy that characterises the Da Ponte operas more than a decade later.

The subject is the relationship between desire and reason, and there are dramatic pre-echoes of Count and Countess Almaviva in the central couple, Sandrina and Belfiore, whose relationship founders into jealous violence and near insanity before reaching a tentative reconciliation. The score, however, is the work of a prodigy who was not yet a genius. Too few of the characters are credibly drawn, too many of the arias form hiatuses in the drama rather than propelling it forward.

A stronger production might have helped. We were promised a new staging by Christoph Loy, who withdrew during rehearsals after "a disagreement about the edition to be performed", presumably with conductor John Eliot Gardiner. In its place, we have a previous Loy version, first seen in Düsseldorf in 1998, revamped by Annika Haller. It's a dull, modern-dress affair, short on wit and perilously losing its narrative focus part-way through.

With the English Baroque Soloists in the pit, Gardiner blazes away at the score with tremendous fire, though the singing is variable. As Sandrina, Genia Kühmeier is disappointing after her exceptional Pamina at Salzburg this summer, while Robert Murray's Belfiore is stronger on nerdiness than charm. Kurt Streit, however, is superlative as Sandrina's would-be lover Anchise, and Camilla Tilling injects some desperately needed humour by camping it up as his gold-digging niece Arminda.

· Until October 7. Box office: 020-7304 4000.