As Adele Adkins herself points out, not so long ago she was playing "to literally two people in a pub in north London". Now here she is headlining a sold-out, 500-capacity venue. Even accounting for a high proportion of family and friends in the audience - which would explain the unusually attentive hush during every song, the remarkable amount of cheering for the enthusiastic but unimpressive backing band and the standing ovation at the end of the show - that is some leap.

Adkins has had the kind of attention in the past few months that could unnerve the steadiest soul. And yet, she seems blithely unaffected. She strides on stage, she sings, she natters inconsequentially, as though she has been doing this all her life, as though there were no difference between the Bloomsbury Theatre and her own front room.

Her casual demeanour is charming, but also gives a workaday quality to the show that emphasises Adele's weaknesses. This is a showcase for her debut album, 19, so she plays it in sequence, rather than the order that might prove most dramatic live. She is also dressed down for the occasion, in loose-fitting, dowdy grey and black clothes that swamp her fabulously curvy figure and suggest she is not as confident about her looks as she claims.

The outfit is worth mentioning because it captures exactly what is wrong with Adele's music. She's worryingly adept at the kind of bland, colourless guff that is so oppressively omnipresent in the background of daily life: music you might hear in shops, on the soundtrack of a soppy romantic comedy, in adverts for feminine products. Current single Chasing Pavements is upbeat but devoid of character. Cold Shoulder is the kind of generic pop tune that is always popular at school discos and weddings. Truly, this is the work of a Celine Dion fan.

There is, though, another Adele: a young woman possessed of a lush, luminous voice, radiating a cocktail-hour sophistication that jars deliciously with her demotic accent and teenage preoccupations. The contrast brings liveliness to Daydreamer, jazzy verve to Crazy for You and gives the apparently syrupy First Love a sharp bite. These songs need no dressing up: Adkins performs them sitting down, accompanied by just her guitar, or a smidge of piano, with all the showmanship in her vocals. It is this Adele, not the insipid, middle-of-the-road singer, who is worthy of all the attention.

· At the Classic Grand, Glasgow, on Saturday. Box office: 0141-847 0820. Then touring.