Roberto Alagna, Barbican Hall, London

It was plucky, not to say defiant, of Roberto Alagna to include the treacherous "Celeste Aida" in his Viva Verdi recital. This was, after all, the aria that precipitated his famous walk-out from La Scala, Milan, in December 2006, when elements in the audience showed their disapproval in the traditional manner. But if he sang it there as he did here, then I can't say I blame them.

Alagna right now is a disconcerting mass of contradictions. On the one hand, he leaves you in no doubt that his is an international talent: he has the voice, the temperament, the charisma. His boyish grin and impromptu "very nice to be here" prior to the tragically intense Macduff aria from Macbeth defused all tension.

With this kind of evening you can get away with that. Just. But technically speaking, he is failing to adjust to the dramatic changes taking place in his voice, and that is worrying. "Celeste Aida" was just one of many instances where sharpening pitch suggested an uncomfortable push at the top. His intonation generally was dodgy, to say the least, and he opted for the cop-out alternative ending of this aria, with the lower repetition of the final line rather than the difficult but magical diminuendo on the final high B-flat.

But in the Macduff aria, the middle and lower registers came into focus, and it was amazing how much more Alagna was able to do with the voice at its darker, grainier, baritonal centre. Beautiful dovetailing, eternal sostenuto, seductively "covered" sound. That's where the swagger now lies, and in the Oronte aria from Verdi's I Lombardi, it was directed at his wife, Angela Gheorghiu, who made a conspicuous entrance in flouncy crimson – appropriate for an evening that included Johann Strauss's Quadrille on motifs from Un ballo in maschera.

Ion Marin drove the London Symphony Orchestra through that like he was bidding for the land-speed record, while the LSO Chorus at times seemed almost lost for words (in every sense), not least when grappling with the storm scene from Otello. Alagna, however, sang the final scene of that opera rather wonderfully. At last the smoky sound and affecting catches in the voice were put to real dramatic purpose.