The 2013 Turner prize is a strange, unbalanced and somehow out-of-whack exhibition. It has the audience fumbling in the dark among old teapots and the detritus of Laure Prouvost's grandparent's living room, being buttonholed by strangers at the behest of Tino Sehgal in an otherwise empty white room, back in the dark to look at the paintings of Lynette Yiadom-Boakye, and getting dusty with charcoal and pastel crayons in a drawing class set up by David Shrigley.  First, the life class. The first life model I ever drew, at art school in the early 1970s, was the wonderfully eccentric and camp Quentin Crisp. Blue-rinsed and wearing nothing but a thong and some nail varnish, Crisp could contort himself into poses you couldn't understand, let alone draw. Shrigley's misproportioned, naked and larger-than-life polyester model just stands there, blinking mechanically, dangling his hairless manhood and occasionally pissing in a bucket. He's surrounded by easels and chairs, the walls about him covered in the public's hilarious, hapless and devoted attempts to draw him.  Taking up the challenge, I went for broke, channelling De Kooning with my own ham-fisted smears. The important thing about the best of the drawings people have made in response to Shrigley's sculpture, is that they are full of character and life: the problem is, no one could possibly ever look like that. It is a great exercise in participation, but Shrigley's sculptures are not nearly as good as his drawings and animated films. They never quite inhabit that dark universe his drawings intimate. Their wonkiness feels too well-made and calculated. Shrigley should have been nominated before, and two of us on the 2004 Turner prize jury wanted him on the list, but were laughed down. Shrigley at his best can leave you with a yawning chasm in your soul, if you have one. By providing us with such a daft model, he invites us to become one of those fictive characters whom we imagine make his drawings, which often look like the mental regurgitations of a madman or an idiot savant. Shrigley's own drawings are absent here. Ours will have to do.  Glaringly spotlit in an otherwise darkened room, the characters in Lynette Yiadom-Boakye's paintings are also a kind of fiction. All her subjects are black, and the grins, the whites of their eyes, a white shirt and white underwear stand out. Her display is both theatrical and frustrating. You have to get up close to see details, and the ways the paint has been handled. It is difficult to take in the paintings in their entirety, the relationships between figure and ground, the nuances: you just can't see them properly. This probably sounds like an old-fashioned complaint. We are used, after all, to seeing poorly illuminated paintings in churches; but there the placement, situation and context add something to their mystery. Here they do not, and feel too much like a conceit.  Not much connects the different paintings – man with rifle, two figures bending, one removing their socks, another figure turning and smiling enigmatically, someone lounging casually on a dune. Her people are often androgynous, but her plays on gender never seem to count for as much as they could: we just say "figure" rather than man or woman. I like this – and that she is inventing a world of characters – but I find the painting itself a bit ordinary. She reminds me of too many other painters – the Belgian Michaël Borremans, whose figures are often similarly engaged in inscrutable acts, Marlene Dumas, Chantal Joffe.  The staging of her paintings here accentuates the otherness of her subjects and dramatises our confrontation with them in a way that the paintings themselves don't manage to deliver. Thinking of the painters who have previously won the prize – notably Chris Ofili and Tomma Abts – only points out that Yiadom-Boakye isn't there yet. I want her to be more risky and more free than she is.  Freedom and play are also at the heart of Laure Prouvost's multimedia installations. This one, called Wantee, was recently shown as her contribution to the Tate exhibition Schwitters in Britain. Wantee was the name of Schwitters's girlfriend, whom Prouvost has woven into the story. Both in the video itself, and in the gloomy, cluttered room that contains it, we take a tour of her grandparents' house, where we are surrounded by her grandfather's homemade teapots, paintings, collages and hapless sculptures.  Prouvost often references her grandfather, a bottom-obsessed conceptual artist who once decided to tunnel to Africa through the living room floor. One day he never came back. Her work here also includes a little pink chamber with a sloping, carpeted floor, where a new video shows us her grandmother's dreams of motorbike-riding, going down the disco, frying eggs on a laptop computer and reinventing the aloe vera plant to grow without thorns.  I preferred the installation Prouvost showed at the Whitechapel recently, after winning the Max Mara art prize for women. All this is too much, too solipsistic. I like Prouvost's sense of fun, the languorousness and silliness of what she does, and her French mangling of the English language, but as with Yiadom-Boakye I keep thinking of other artists who tread similar territory. It is difficult to look at Prouvost without comparing her to Swiss artist Pipilotti Rist, who just does it better.  No one does it quite like Tino Sehgal. Nominated for his recent Tate Modern Turbine Hall commission, and for the wonderful, immersive work he showed at Documenta XIII and, recently, at the Manchester International Festival, you knew he was either going to repeat himself or to set up a new – perhaps even more confrontational relationship – between the audience and his participants than before. This Exchange was originally devised in 2003, and is a reminder that Sehgal's work is neither entertainment nor pure performance. I don't think he is interested in novelty.  A number of people hang around in a bare, white space, and draw us into conversation, asking us: what do we think about the free market? What do we think about exchange? The conversation spirals, into personal experience, fears and hopes for the future. We end up talking about Derry's high unemployment, the economic crisis, the problems people face here. Sehgal's "interpreters" are local, a mix of young and old. If we join in the conversation we are offered £2, which we can claim at the exhibition entrance, if we repeat a password. It seems mean to ask for the cash, though this is a continuation of the idea of exchange. Should I ask for it or not? Am I so craven? Where does the £2 come from? Is it real?  When the shortlist was announced, I said Sehgal should win. He is the most original and provocative of the artists here. His work has developed in unexpected ways, and at a level none of the others here have achieved. He makes us think. In exchange, he should win the Turner prize.  • Follow Adrian Searle on Twitter
With its tea parties, cash giveaways and life drawing drop-in, this year's Turner prize exhibition is fun, engaging and democratic – but is the art any good? Adrian Searle gives his verdict