Jonathan Miller's much-loved production of The Mikado for English National Opera is now 25 years old and well remembered. But not, I confess by me. My last experience of Gilbert and Sullivan was on the other side of the curtain, as a sister, cousin or aunt in a school production of HMS Pinafore, an experience sufficiently scarring that I resolved never to go to a G&S opera again. But I admit that forty years was probably overdoing it, and I went along to the Coliseum last night fully bent on enjoying the evening.

The production is nothing short of superb. Miller dumps a cod-Japanese setting in favour of a 1920s art-deco grand hotel: Greek columns and elegant windows abound, everything is painted in shining white, the lights are bright, and complicated things are done with stage raking to give the impression of many rooms. The attention to detail is quite exceptional, no more so than in Sue Blane's costumes, which are exquisite. Whether it's perfect evening dress for the men, kimonos, school uniform or ruffled wedding dresses for the girls, or blazer and boater for the boyish hero Nanki-Poo, everything is done to a quality and historical accuracy that is simply jaw-dropping.

It's not just the static elements of the production that impress: the choreography and movement around the stage all add to the fun, with the mock "grand opera ballet interlude" scenes particularly entertaining, and acting and dialogue were all well above the usual operatic standard. Singing was mostly up to the mark, in spite of diction suffering from the need to fill a large opera house with sound. Alfie Boe sang Nanki-Poo in a light, clear tenor with oodles of charm. I struggled to hear Sophie Bevan as Yum-Yum in the first act, but she sung her showpiece aria The sun, whose rays are all ablaze beautifully, and got better as the evening went on. The show is dominated by the comic interplay between Ko-Ko and Pooh-Bah: Richard Suart is a G&S veteran who can clearly play Ko-Ko in his sleep and carry a whole performance as he does it, and Donald Maxwell joined in with gusto and a lovely soft Edinburgh accent.

But the orchestra, under conductor Peter Robinson, disappointed. The whole thing lacked verve and fizz: I had the impression of bright, cheerful music struggling to be let out of its cage. I was particularly disappointed by the celebrated Gilbert "patter songs" like A more humane Mikado and There is beauty in the bellow of the blast, which just didn't come off with the desired level of excitement.

A couple of caveats, though. I was sitting far on the right-hand side of the stalls, where the orchestral sound at the Coliseum does tend to get out of balance: the trumpet and trombone section can overpower any subtlety of phrasing. Also, it's fair to say that Sullivan's music is a strange animal. On the surface, it's a parody of just about every operatic style that preceded him: we get Italianate arias, Donizetti-like opera buffa duets, French Grand Opera scenes and choruses, English pastoral melody - only Wagner is (wisely) absent. It's all cleverly done and some of the music is very lovely indeed, but the assembled whole is rather patchwork. Soon after The Mikado was written, Sullivan wrote that he had "lost the liking for writing comic opera", and to my ears, it comes through in the music that Sullivan dearly wanted to write music that was more important and fulfilling than the Savoy Opera style permitted.

Overall, therefore, to use a phrase from Gilbert and Sullivan's time, a curate's egg of an evening, with the music rather letting down some decent singing and a top class dramatic production. It may well improve as the run continues.