Theatre: Don't give up the night job, Eddie

Long, long ago, in a land of volcanoes and coral reefs, where the warm Pacific breeze ruffles the coconut palms, the local inhabitants came up with a concept that was to become central to alternative comedy: the taboo. From Lenny Bruce to Eddie Izzard, alternative comedy can be seen as a sustained effort to shed light on those areas of life that still qualify for the one Polynesian word that we all know.

Back in the 1960s, Lenny Bruce was making his name by getting arrested for breaking the taboos surrounding four-letter words, six-letter words and 11-letter words (if you're counting, that last one ends with "sucking"). Bruce believed that by constantly repeating "nigger", "yid" or "greaseball" you could rob these words of their violence. He called his autobiography How To Talk Dirty and Influence People and if that sounds facetious, well, he was in earnest. Bruce believed in logic and laws, and for all his hilarity he was more than a bit rabbinical. It's no surprise that Bob Dylan named a song after him.

If Bruce's stage act was edgy, angry and disturbing, then Eddie Izzard's performance in Lenny, Julian Barry's biographical play, is only loveable and untroubling. For the director, Sir Peter Hall, the idea of casting Izzard as a stand-up comic with a gift for surreal flights of fancy was probably irresistible. If so, it was only a so-so idea. If you are doing a play about a highly individual free-wheeling comic, the last person you need is another highly individual free-wheeling comic. You want an actor.

Izzard turns in a Herculean performance as Lenny. He throws everything at the role, from the uncompromising opening - where he is naked - to his death from a morphine overdose at the end. He's daring, exhaustive and often funny. But as he grabs at words, stutters in the middle of riffs or hurries through the domestic scenes, he looks as if all he wants to do is get on with his own material. Hell is other people's lines.

There are two types of dialogue Izzard likes. He can have a conversation between various characters (so long as he does all the voices himself) or he can talk to the audience and share his thoughts. What he doesn't look comfortable doing is talking to these other guys standing around called actors. They work to another beat. It's as if a jazz player - who keeps wanting to cut loose and show us what he can do - finds himself trapped in the middle of an orchestra.

His black hair, sideburns and fleshy face look more like Elvis than Lenny. He gives us the Lenny Stance, where the elbow perches on the microphone stand and he gives us the Izzard Walk, those lumbering steps that suggest he's about to play lead guitar. He does the famous routines well. When he's repeating the words "to" and "come" over and over again in a prose poem of sexual anxiety or heading off into an extended fantasy about Jesus and Moses visiting St Patrick's Cathedral, then Izzard is at his best. When he asks the lepers in the Cathedral not to touch anything, Eddie and Lenny make a perfect match. These sections win the audience right over, and then, in the bits in between, they slip out of his grasp again.

It's the scenes from Lenny's life - which interweave with the routines - that sink this overlong production. We watch in disbelief as Izzard takes his wife Rusty (an impressive Elizabeth Berkley) back to meet his mum, or when, after they're divorced, he's looking after his little baby daughter late at night. These scenes are preposterous, really: devoid of psychological truth or authentic interaction. The set-pieces that require a world to be conjured up on stage - the courtroom or the night- club - are paper-thin. Too often the houselights go up and we feel the show's energy haemorrhaging away.

Lenny was first staged five years after Bruce's death. Three years after that Bob Fosse directed Dustin Hoffman in the movie. This black-and-white version is a treat. There's a clear, controlled aesthetic (it's beautifully shot), tightly organised material and a fervid pulse to the narrative. You enter the world of Lenny Bruce. The West End revival has none of this attentiveness.

We are presented with a ragbag of styles. In the courtroom scenes, for instance, the rest of the cast wear masks as if in a Greek tragedy. The jazz band are on stage. William Dudley's set has a catch-all flavour to it. Glass screens form the walls of the courtroom and back projections gives us the exterior shots of neon signs and nightclubs. The costumes look as if they've been borrowed from a period musical. If I was Eddie Izzard I'd cut out all the biographical stuff and just go out there and do the routines as a homage. The rest is beneath him.

Queen's, W1 (0171 494 5040) to 16 October