Les Troyens, Royal Opera House, London Zanetto/Glanni Schicchi, Opera Holland Park, London Dr Dee, Coliseum, London

A gargantuan and overblown Berlioz opera tests its audience as much as its outstanding soloists, chorus and orchestra

Ever since its first performance in 1863, Les Troyens has been a problem. Only three acts of the opera were staged at the Paris première, in a production that Berlioz himself described as "in some places irrelevant and in others positively ridiculous". Having made "a wretched impression", the Royal Hunt and Storm was cut from the second performance. Next to go were the scene between Narbal and Anna, the second ballet, and the homely, bassoon-peppered sentries' duet. By the end of the run, 10 numbers had been excised from an already truncated score.

It would take a heart (or a bottom) of stone not to envy the Second Empire Parisians in the second half of David McVicar's production. Besotted by notions of authenticity, few of today's conductors would allow such tinkering with a rarely performed work, though when Berlioz's greatest champion, Colin Davis, last presented both halves of Les Troyens in one evening, even he omitted the ballets. At five-and-three-quarter hours, the uncut score is a challenge for the audience as well as performers. Like the Trojan hero Enée, and Berlioz himself, McVicar loses focus in the heat of the Carthaginian sun and the witless pantomime of dancing builders, sailors and agricultural workers (choreography by Andrew George), who scramble ouchily over a scale model of the city in designer Es Devlin's tiered set.

This, then, is Carthage, a concave sandcastle decorated with Moorish lanterns and scatter cushions. More arresting is its opposite, the convex steam-punk citadel of Troy. Here, in the funerary tableaux, the drapery of veiled mourners, the grand hysterics of Cassandre's visions, the symbols painted on her palms, the entrance of the Trojan Horse and the swoon of the Trojan women's suicide, McVicar balances the intimacy and grandeur of Berlioz's vision. But only in the torment of Enée's "Inutiles regrets", the curse of the Carthaginian chorus and the closing apparition of Hannibal (composed, like the horse, of weaponry), does he recapture that energy, having dawdled touristically through Acts III and IV.

Fury drives the most powerful moments from the chorus, whose coarse, edgy sound is a match for the phalanx of extra brass in Antonio Pappano's orchestra. The colours from the pit are frequently dazzling – the strings smoky and predatory in Anna Caterina Antonacci's "Malheureux roi!" – but the tempi idle dangerously. Eva Maria Westbroek's Dido is goofy and girlish, unregal. It's a generous, volptuous sound but neither she nor Bryan Hymel's Enée look transported by desire in "Nuit d'ivresse". Vowels nasalised, consonants crisp, top notes heady, Hymel is arguably better suited to this role than Jonas Kaufmann. With strong support from Brindley Sherratt (Narbal), and a Cassandre of matchless complexity and charisma from Antonacci, there is much to recommend Les Troyens. But in delivering the uncut version, and in focusing too much on spectacle and silly dances, McVicar and Pappano have exposed the weaknesses in Berlioz's problematic epic.

Opera Holland Park serves up a rare dud in Martin Lloyd-Evans's production of Mascagni's Zanetto. The music is slight and slender, with a delicate a capella vocalise for an overture, the plot non-existent. Financial constraints are evident in Susannah Henry's set, which reappears in a different guise in the second opera of the double-bill, Gianni Schicchi. Casting Mascagni's courtesan as an actress is a good idea but needs a dose of Sunset Boulevard glamour. Janice Watson's Silvia seems more petulant than wistful, her interest in Patricia Orr's bell-toned Zanetto, a little creepy.

Torpor is dispelled in Gianni Schicchi, where conductor Manlio Benzi delivers a performance of considerable snap and colour from the City of London Sinfonia. Aside from an over-long dumb-show and the obligatory rose-tinted pause for Anna Patalong's "O mio babbino caro", Lloyd-Evans's production is fast-moving, superbly cast with Alan Opie in the title role and a wonderful ensemble of grotesque cousins.

Extended for its run at the Coliseum, Damon Albarn and Rufus Norris's Dr Dee has some exquisite moments. Afloat in a barge with a time-travelling, intercontinental consort of kora, theorbo, African drums, harmonium, recorders, dulcian and lirone, Albarn sings to his guitar while archetypes of England's real and imagined past (punk, city gent, puritan and fop) fall backwards into the unknown. Dee's lifestory unfolds as a masque of breathtaking beauty beneath the iconic figure of Queen Elizabeth I. Familiar from the Blur hit, "Tender", Albarn's trademark technique of layering naive melodies sags when the pit orchestra joins in. Too much of the incidental music sounds like recycled Michael Nyman, portentous and plonky. In a mix of vocal styles, from Anna Dennis's melismatic Katherine Dee, Melanie Pappenheim's blanched Spirit, Christopher Robson's shrill Kelley and Steven Page's baleful Walsingham, Paul Hilton's Dee sounded uncomfortably West End.

'Les Troyens' (020-7304 4000) to 8 Jul; 'Zanetto'/'Gianni Schicchi' (0300 999 1000) to 12 Jul; 'Dr Dee' (020-7845 9300) to 7 Jul

Critic's Choice

Performers at the City of London Festival this week include the Orchestra of the Age of Enlightenment, the Brodsky Quartet and Christian Lindberg in venues across the Square Mile. Cheltenham Music Festival opens with Britten, Tippett and Finzi from James Gilchrist, Anna Tilbrook and the video artist Netia Jones, Brahms from The Nash Ensemble, Debussy from Jean-Efflam Bavouzet, Ravel from Melvyn Tan, and The Opera Group's Babur in London.