La Rondine, Royal Opera House, London

Newcomers to Puccini's La Rondine will experience an acute attack of operatic déjà vu . They'll be thinking Die Fledermaus in Acts I and II; they'll be wondering why Bullier's reminds them so much of the Café Momus in La Bohème. And isn't that final act a kind of hybrid of Manon Lescaut and La Traviata? Enough already. When a show is as easy on the eye and ear as this one, should anyone care? Best not to.

Puccini planned to get rich on the proceeds of La Rondine. It was written for Vienna, where he hoped to replicate the unimaginable success of Lehar's Merry Widow. There's even a hint of it in the fizzy opening bars of the prelude. Shortly thereafter comes the poet Prunier's song "Doretta's Dream", as surefire a hit as Puccini ever penned; and he does it again in Act II with a waltz song to rival anything in Lehar or Strauss. But in striving to be someone else, Puccini succeeds only in becoming a shadow of himself. As music drama, La Rondine is a non-starter – entirely cosmetic in effect.

Enter Roberto Alagna and Angela Gheorghiu. Should we be reading anything into the fact that they have so enthusiastically made La Rondine their own after nearly a century of neglect? Probably not. But an opera that achieves its effects so lazily and so blatantly hardly presents a challenge to either of them.

The gifted Miss Gheorghiu wears Puccini's music as she does Franca Squarciapino's 1920s costumes in this picturesque Nicolas Joël staging (sets: Ezio Frigerio, with a little help from Gustav Klimt). She positively ladles on the portamento, melting all hearts with "Doretta's Dream". Make no mistake: this is a great voice which knows how to place the money notes so's no one will ever feel short-changed by them. The technique is absolutely secure, the execution effortless, the sound gorgeous.

So why the niggling feeling that this is as good as it gets? Time will tell, of course, in more demanding roles than Magda de Civry, the kept woman with a guilty conscience. But my feeling is that Gheorghiu will need to stretch herself more artistically if her singing – beautiful, even thrilling, though it is – is to say something lasting and meaningful. We're not yet seeing behind her eyes.

Her Ruggero (in every sense), Roberto Alagna, would have benefited from borrowing a little of his wife's portamento to loosen up and lend some enticement to his phrasing. It was notably stiff in his opening aria "Parigi!". I wish, too, he'd find more opportunity for persuasive piano singing. The little half-shades that mean so much. Even so, no one could deny he gave value for money.

The evening was all about value for money. Even the opera was about value for money. Character surfaced fleetingly in the double act of Lisette (Cinzia Forte) and Prunier – an elegant performance from Charles Workman, whose singing came close to upstaging Alagna on points of style. But any semblance of truth was to be found only in the lovers' prolonged kiss in Act II. Suddenly, we felt we should leave them to it.

To 22 May (020-7304 4000)