"Blessed are the Average" reads a digital signboard in the newest work from Britain's groundbreaking DV8 Physical Theatre. Surely, in terms of art and entertainment, this is an inaccuracy. Don't most of us attend performances in the hope of seeing extraordinary people doing extraordinary things? But what qualifies as extraordinary? And in the wider arena of society, who are the arbiters of taste, beauty and acceptability?

These are some of the central ideas kicked around by the director Lloyd Newson and a cast of 17 in can we afford this. The engaging but uneven 90-minute show is the opening event of this year's Dance Umbrella, London's annual festival of international contemporary dance.

Newson, champion of the unpretty and unconventional, prides himself on perpetrating a more honest, provocative brand of movement-based theatre. Here he's gathered a particularly motley crew, from the powerful legless dancer David Toole to mature DV8 stalwart Diana Payne Myers. She says she has had four different lovers, all under the age of 30, since qualifying as an OAP. At least that's what she sweetly states in a mock meet-the-contestants parade, and why should we doubt her?

During this same passage, a cast member tells us he sold heroin for two years to support his dance training. Another blithely announces he has AIDS.

These are declarations, not confessions. Each contestant wears a ribbon, as if awarded a prize simply for being him or her self. The false notion that everyone's a winner is Newson and company's heavily ironic point.

The collage-like production, set on a ramped, walled expanse of grass-like carpet studded with trapdoors, is one of DV8's lighter-spirited efforts. It's like a garden party gone awry. There is literal clowning at the start but the humour always has serious underpinnings. This makes for a user-friendly, yet confrontational, evening that balances text and movement.

During a smiling ensemble balloon dance, a more conventionally built man slips in to replace the large (26 stone) American dancer Lawrence Goldhuber. To delicate waltz music, Toole circles beneath Amazonian classical dancer Kate Coyne's drawbridge legs. Later she bends forward while he rides atop her hips, as if her long legs were his.

There are other fine duets, plus an unexpectedly poetic, surreal section in which the stage appears to be covered in rolling clouds. Some parts feel vague and arbitrary, and the show is overpopulated. But, as with all of DV8's work, it demands a thoughtful response.