Liverpool has the only full-scale biennial in Britain, for which it commissions new work by artists from all over the world. This year's is timed to coincide with the biannual John Moores painting prize exhibition, and the annual New Contemporaries student show, so it should be hot - especially as Liverpool celebrates its year as European Capital of Culture. Sadly, it isn't. I have seen every Liverpool biennial (this is the fifth), and each has left me flat. Maybe it is too undecided about its role in the cultural life of Liverpool, and its place alongside other European biennials.  The show opens at the same time as a shopping precinct and numerous new buildings arise in the city centre. The redevelopment is depressingly generic. So, in its way, is this biennial, which is called Made Up. It isn't sure if it wants to tell stories, to forget and forgive, to put on an act or, in Liverpool parlance, feel happy and satisfied with itself - made up.  The work installed at the Bluecoat Gallery is the most playful. Tracey Moffat's compilation of footage from disaster movies presages a rumbustious and very satisfying end of the world; there are the Royal Art Lodge's 300 funny, often ghoulish little paintings from Canada; and Sarah Sze has set up some cobbled-together sculpture, which infests the building. These are all weirdly engrossing, even if one has seen such things before.  At Fact, Liverpool's Foundation for Art and Technology, an extremely aggressive projection with pulsating lights by Ulf Langheinrich is meant to put the viewer into a state of hallucinatory semi-consciousness. You have to wear special glasses to watch it - always a bad sign. A "stereoscopic/3D and cinemascopic" video was mesmerising a large audience on my visit. They drooled on the sofa, slack-jawed, as the lights flashed relentlessly. I ran.  Upstairs, people were listening to a sound piece with their heads enclosed in 1950s salon hairdryers. Meanwhile, Korean artist U-Ram Choe's sculpture, hanging from the ceiling on the ground floor, had clearly been installed in the wrong building. This whimsical mechanical object, which looks like a giant grub in a corset, would be better as a decoration in a shopping mall. Ai WeiWei's spider, suspended upside-down on its twinkling web over the courtyard of Exchange Flags, at least has a bit of magic to it.  Annette Messager's pneumatic puppet theatre, installed in the auditorium of the former ABC cinema, was, I think, also intended to be mysterious and a bit spooky, but it was a disappointing rerun of her installation in the French pavilion of the 2006 Venice biennale. Black silk rolls over the cinema seats in a giant wave, powered by compressed air, and a creepy skeleton and bat-like hands jangle about where the cinema screen used to be. A flaccid globe of the world slowly deflates. I know how it feels.  David Altmejd's The Holes also felt like a replay of the sculptural installation he showed in the Canadian pavilion at Venice in 2006. A huge, yeti-like creature reclines in an unworldly landscape, like a monstrous, mortally wounded table decoration. This is overwrought, sci-fi gothic piffle. Alison Jackson's lifelike waxwork of George Bush, who sits in the Tate cafe peering perplexedly at a Rubik's Cube, is a funny photo opportunity for gallery visitors, but not much else.  On the top floor of Tate Liverpool, Vancouver-based Rodney Graham shows a light box image of the artist dressed as a top-hatted character in a western saloon, being made to dance by a couple of rowdy cowpokes. I like Graham, but his contrived photographs are beginning to look like weary equivalents of 19th-century narrative paintings, which is precisely how they are intended.  Stuck in the middle of Tate Liverpool is a space dedicated to drawing. The artists here blur into one another in an irritating and confusing way, cancelling out their individuality. The best things here are the dozens of framed drawings compiled by Slovakian artist Roman Ondák, who asked his family and friends to draw their visions of the city of the future: they are full of variety, wit, horrible futuristic architecture, and good and bad drawing. This is a rich and affecting project.  The most complex and apposite work anywhere is Omer Fast's specially commissioned video, Take a Deep Breath. There has been a suicide bombing; the setting is Israel, "at a falafel place somewhere in Prophet Street", although we are also on a movie set, in what is meant to be the US. Blood-spattered actors queue for lunch, and there is lots of grim humour. Although the film is very funny, we keep being reminded of a real bombing, which apparently provoked the story. This is both a spoof, and a genuinely macabre and sophisticated filmic labyrinth.  Take a Deep Breath is worth the trip to Liverpool alone. Much else isn't. However skilfully the organisers negotiate the financial problems and local politics that dog every such event, however much they commission, there is something missing. The problem here is a lack of flair and vision, and the redundancy of a lot of the art being shown. There are doubtless too many biennials. And there is probably too much mediocre art that nobody, not even the artist who made it, needs.  · The Liverpool Biennial runs until November 30. Details: biennial.com
There's a real mish-mash of work at this year's Liverpool Biennial. It desperately needs a little flair and vision, says Adrian Searle