Blunted needle: Mark Pappenheim on Elijah Moshinsky's new production of Berlioz's Beatrice & Benedict in Cardiff

Next to Virgil, only Shakespeare held equal sway in Berlioz's personal pantheon. The Mantuan was, of course, a constant childhood companion. Yet even the passions aroused by the 10-year-old's stumbling reading of the death of Dido - though destined to erupt 40 years on in the epic heartache of Les Troyens - paled before the bouleversement of the 24-year-old's first encounter with the Bard.

In Harriet Smithson, Kemble's leading lady, Berlioz found not just the soul of Shakespeare, but his very own Ophelia and Juliet, rolled into one. Yet, while Shakespearian themes permeate Berlioz's work - from the ghostly Hamlet chorus and magical Tempest fantasy of Lelio, to the ravishing 'In such a night' duet shoehorned into The Trojans from The Merchant of Venice - it was not until his late- fifties that he attempted a real Shakespearian opera.

By then, worn out as he was by the frustrations of trying to get The Trojans staged, it was largely a case of all passion spent. Yet, in fashioning his own text for Beatrice and Benedict by stripping Shakespeare's Much Ado of all but its comic sub-plot, Berlioz ensured that passion - and its unaccountable growth in the human heart - remained the key to his only comedy.

'A caprice written with the point of a needle' he called it. That sharpness of wit is certainly there in the overture, deftly etched by the Welsh National Opera orchestra on Thursday night under John Nelson's experienced direction. It's hard to imagine a better image of the rapier repartee of Shakespeare's sparring partners than the woodwind's busy tonguing. That's just the problem: nothing else in the opera matches the cut and thrust of its prelude. Yes, there are wonderful things - none more so than the nocturnal duet for Hero and Ursula (Rebecca Evans and Patricia Bardon), its heady mix of Mediterranean warmth and the scent of roses wafting seductively across the seas from distant Carthage.

But Berlioz's cut-down dialogue, even as reworked by the director Elijah Moshinsky, leaves out most of the slanging- matches. A red-headed pre- Raphaelite bookworm, with the air of a young Joyce Grenfell and the voice of a second Kathleen Ferrier, Sara Fulgoni makes a nervy Beatrice, better perhaps as Lady Disdain than as Lady Tongue, but collapsing touchingly into tears at the sound of her cousin's off-stage marriage hymn. As Benedict, Donald Kaasch might have made a more Malvolio-like transformation upon resolving to become 'horribly' in love, but he soars happily in the high-flying tenor part, before stopping his mistress' mouth with a kiss.

Tonight, 1 Oct, New Theatre, Cardiff (0222 394844); then on tour