Danielle de Niese, Barbican, London

"Myself I shall adore," sang Danielle de Niese at the Barbican, incarnating Handel's sexually voracious Semele. But this girl hardly needed to, so deafening is the chorus of approval in which she basks. She's the ultimate classical poster-girl, deployed to lethal effect by Glyndebourne, first in 2005 as the sexiest Cleopatra in living memory in Giulio Cesare, and now as a raunchy 21st-century version of Monteverdi's mixed-up Poppea.

De Niese dances as well as she acts, and looks great on film: opera directors are fighting for her services. Decca has brought out her debut record of Handel arias. Hot doesn't get hotter. But listening to that CD isn't pleasure unalloyed. There's a hard edge to her voice, and you hear effort in her coloratura, which lacks finesse. Shorn of her irresistible stage presence, 29-year-old de Niese the singer is still an incomplete artist.

So it was good that we had her in person, in this "Mostly Mozart" concert with the Academy of St Martin in the Fields, under the baton of Garry Walker. After a beautifully judged performance of Haydn's Symphony No 70, it was time for the main event – three Handel arias. De Niese swept on, looking very South Seas in a flouncy gown: she was sighing and palpitating with gratified desire before she'd had time to sing a note.

How did she sing? Decently, but that wasn't the point: the first aria, "Endless Pleasure", was Semele's celebration of a successful seduction, and de Niese dramatised it to the hilt. Next she sang the sublime lament from Rinaldo, "Lascia ch'io pianga" – "Let me weep over my cruel fate". She paced the music well, but the point here lay in her high-tragic gestures: another mini-drama, which she finally punctured with a "didn't-I-do-well" grin.

Semele's love-song to her image in the mirror became the expected comic turn, but by the end she had taken over the conducting as well, and turned the whole audience into fans. In the interval, the record shop piled her high and sold her fast.

After a fine performance of Mozart's Flute and Harp Concerto, with Adam Walker and Sally Pryce as soloists, it was time for Mozart's "Exsultate, Jubilate", de Niese's grand finale. This ecstatic work is all about beauty, but de Niese's performance was all about itself. The audience clamoured for more. Given her ability to carry an entire show by sheer charisma, her operatic career is assured, but this brief outing pointed to the possibility of a career of a very different sort. Does showbiz beckon? Big-time, I think.