Joss Stone, Brighton Centre, Brighton <!-- none onestar twostar threestar fourstar fivestar -->

Joss Stone has crammed a lot into her short life. The 18-year-old soul sensation from Devon has duetted with everyone from James Brown and Gladys Knight to Mick Jagger, bagged several awards and memorably confused Bob Geldof with Gandalf while recording the Band Aid single.

Stone has also blazed something of a fashion trail with her blow-dried hippie chic, an aesthetic reflected here by the woven rugs scattered on the stage and the scarf tied to the mic stand. Even a lucrative deal with the clothing chain Gap doesn't seem to have convinced her of the merits of shoes.

But Stone would be a mere X Factor wannabe without that voice, a remarkable instrument often compared to Janis Joplin's white-soul wail. Despite her irksome habit of singing in an American accent, it's a relief to find that Stone avoids the vocal acrobatics favoured by so many peers. And, while there's plenty of emoting, you don't doubt her sincerity. But when the shock of the voice wears off, you're left with - what? A series of smooth funk and contemporary R&B numbers, occasionally laced with a Kravitz-esque guitar solo.

The whole show is a determinedly middlebrow affair, inoffensive to the point of blandness. "Young at Heart" is a humdrum tale of thwarted love; "Some Kind of Wonderful" starts well, but then morphs into a ghastly love-in in which Stone and her trio of backing singers tell each other how wonderful they are. But the main problem is the gulf between singer and voice. Stone comes across less as a seasoned soul diva than the schoolgirl who, in another life, she would still be, prone to fiddling with her hair and giggling. The lyrics don't always sit right, suggesting a woman who has not just been around the block but steamrolled right through it. By contrast, Stone exudes a youthful wholesomeness, which may account for all the pre-teens in the audience.

The hit "Right to Be Wrong" is more convincing, dealing with the inevitable folly of youth, while her reinterpretation of The White Stripes' "Fell in Love with a Girl" (retitled "...with a Boy") is an authentic take on the first flush of love.

You can't begrudge Stone her success. Right now, however, her age works against her. She is clearly in it for the long haul, so would it be asking too much to let her grow up first?

Touring to 20 December ( www.jossstone.co.uk)