Jessie J, Scala, London

It perhaps wasn't the wisest move to turn up to the gig of the most hotly tipped artist of 2011 merely seconds before she was due on stage. Squeezing into the packed, sweltering room, an impatient crowd jostled and elbowed each other, stood on tiptoes, anything they could to catch a glimpse of the intriguing new star. Even poor Lulu had to make do with sitting on the floor of the balcony, peering through someone else's legs.

But such is the interest in Jessie J right now. After scooping both the Brit Awards Critics' Choice and the BBC Sound of 2011 poll, can the 22-year-old from Essex live up to the hype?

This moment has been a long time coming for Jessica Cornish, though, and the girl has paid her dues. After following the much-trod career trajectory of your typical pop wannabe (the West End, a stint at performing arts school, a short-lived girl group), she was signed to Universal Republic in the US, penning tracks for the likes of Alicia Keys and Justin Timberlake.

Now it's her turn in the spotlight and, boy, is she determined to make the most of it. You get the impression that tonight's gig is a showcase for the singer to share her personality and vision. Filled with industry folk, fans and friends, the show is part stand-up comedy routine, part motivational talk, peppered with a few songs in between.

But what starts as endearing quickly turn mawkish, as Cornish explains that she's just being herself and she's only a girl trying to live out her dream (and we can too if we believe in ourselves!) To prove she really is just a "normal chick", she likes to say things like, "Some snot just came out of my nose." It feels like a slightly desperate plea to be accepted and liked.

It seems to work anyway, as most of the room cheer in support and are somehow already singing along to songs from a debut album that is yet to be completed.

At least she looks the part. Dressed in a green corset and some dangerous-looking heels, it's impossible to take your eyes off her and she is far more striking than she appears in the aggressive press shots that have been doing the rounds.

But the music is decidedly underwhelming. After her stomping first single, "Do It Like a Dude", which is currently sitting at number two in the charts, it seems we can look forward to a bunch of boring, blousy ballads such as "Who You Are", with insipid lyrics like "Tears don't mean you're losing/ Everybody's bruising/ Just be true to who you are". The fact that this is a girl who helped write "Party in the USA", one of the best pop songs of recent years, makes it all the more disappointing. She's joined on stage by Devlin for next single, "Price Tag", a jaunty, if unexceptional, track that chugs along nicely, but really it's hard to find anything new or remarkable here. Even her fantastic and powerful voice has a propensity to irritate, with the never-ending theatrics and tics.

There's no doubt Jessie J is a talent. But at the moment she's not quite the deliriously exciting prospect some would have you believe.