Béatrice et Bénédict, Glyndebourne

Locations count for little in most of Shakespeare's comedies. Only a literal-minded director would, for instance, insist on Messina, Sicily as the setting for Much Ado About Nothing. In Béatrice et Bénédict, on the other hand, Berlioz injects his very odd Bardolatry with lashings of the southern Italian light and atmosphere he loved so much.

So turning it all grey as Laurent Pelly does and putting everyone into boxes except the loving enemies who think outside them - get it? - goes against the grain. But then colour is leached away from just about everything in this far from vintage Glyndebourne evening

Berlioz doesn't make it easy to animate his oblique take on the much more nuanced original. None of the crucial situations in Shakespeare - the gulling of Beatrice and Benedict into believing that each is loved by the other, the crucial scene where they admit what they've been hiding beneath their barbs - gets set to music. The whole plot whereby an initially anaemic - and, in the right hands, not so secondary - pair of lovers find themselves emotionally challenged by the machinations of a villain who doesn't feature in the opera goes out the window. That makes soprano Héro a cipher with lovely music, her fiancé Claudio a non-part and the verbal fencers defenceless without something to react against (who can forget Beatrice's "Kill Claudio" in a good production of the play?) To be fair, Pelly does encourage Agathe Mélinand to restore more Shakespearean lines to the dialogue, but it's not enough.

The plus ought to be the unexpected intermezzi which are the highlights of the score - the duet for Héro and Ursule, the trio in which similar music finds them joined by Béatrice (pictured above), the poetry of the ensuing chorus. But all Pelly can find for the usually ravishing nocturne is a box with a wedding dress inside while grey skies persist behind (it was some compensation that the real grey skies had given way to sunshine as we emerged at the interval from this disappointment). It's the worst kind of production in which an idea is allowed to run riot and dominate an entire show - though Pelly's regular set designer Barbara de Limburg, trademark creator of the supermarket witch's house in his superb Glyndebourne Hänsel und Gretel, works wonders within the narrow stylistic exercise.

The voices don't help. Sophie Karthäuser, Héro in a terrible blonde wig for the first half of the run - pray that Anne-Catherine Gillet is better if you have tickets for the second - lacks the lyric-soprano warmth just as Stéphanie d'Oustrac has no sensuality in her distinctive mezzo (though she's a vivid stage presence and can at least sing pianissimo in her aria, the less disappointing of the two big solo numbers for the ladies). At least Karthäuser blends well with the Ursule of Katarina Bradié - not the case with the two singers at the awful RSC Shakespeare gala earlier this year.

It's true that Glyndebourne lost its intended Héro, Hélène Guilmette, and, for the whole of this season, its brilliant chief conductor Robin Ticciati, well on the way to recovery after an operation for a herniated disc. His replacement, Antonello Manacorda, is competent and precise but lacks élan, though the London Philharmonic Orchestra plays well throughout; I was saddened but not surprised when a newcomer told me she found the overture a bore, because in the right hands it's a cut-and-thrust gem.The much-touted Bénédict, Paul Appleby, starts brightly but sounds rough in the upper register when he should ping out his seeming insouciance.

The only other role of any significance is crass music-master Somarone, in the divertissement Berlioz provided to substitute for the knockabout of Dogberry and Verges. Let's face it, he's not funny, though Pelly and the admirable Lionel Lhote do their best. The Glyndebourne Chorus (pictured above with Lhote) are the real stars. They get some lovely music as well as Pelly's trademark crispness of mass semaphoring, but they can't claim to stand alongside ace soloists, as their 1992 counterparts did when Glyndebourne took over the Royal Festival Hall during the construction of the new house was taking shape (such memories of Anne-Sofie von Otter, Dawn Upshaw, Jerry Hadley, Jean Rigby).

The best solo voices are the flutes which punctuate the Nocturne. That would suggest that there's not enough to praise; sorry, you're in for a mostly dreary evening if you have yet to see it. With the new Barber of Seville also not as funny as it should be, that makes two misfires for Glyndebourne on the new productions front; by all accounts the failsafe Grandage Figaro shines brighter than ever this year with a superb cast, and the vintage Peter Hall production of A Midsummer Night's Dream coming soon shouldn't disappoint. A greater Berlioz homage to Shakespeare, Roméo et Juliette, should make amends at the Proms on Saturday.

• Béatrice et Bénédict at Glyndebourne until 27 August