Too Marvellous For Words, King's Head, London

Accentuate the positive? Not here

Nothing could make me dislike Johnny Mercer – could I dislike sunshine? – but Alvin Rakoff's musical certainly tries. Presenting the dapper, witty lyricist as a dim-witted hayseed, a rancorous drunk, and a philanderer who excuses himself by telling his wife he never loved her, Too Marvellous for Words does its best to take the glow off such classics as "I Remember You", "Fools Rush In", and "That Old Black Magic". But while I can dismiss this unpalatable picture, I'm worried that other images from the show may have seeped into my unconscious.

Played by Andrew Halliday, Mercer is depicted in scenes that lurch from embarrassing to ridiculous to bizarre. With his trousers rolled up to show that he's a small boy, he capers about with a lollipop the size of a "stop" sign. Mercer's duets with his father don't end at death: Dad returns in a sheet, with feathered wings, to warble "This Time the Dream's on Me". Pursuing a woman with "Something's Gotta Give", Mercer is in turn pursued by the show's other male singer, a Robin Cook lookalike who, in wig, dress and high heels, picks him up and carries him off. The show also has time for crassness. Alone on a bar stool, Mercer laments that his songs make everyone happy except for "one important person – me".

Known as "the sentimental gentleman from Georgia", Mercer teamed up with Jerome Kern, Harry Warren and his alter-ego Hoagy Carmichael, but his offhand optimism and liquid, brooding melancholy made him the ideal partner for Harold Arlen. These blackest-sounding white men in the business produced "Accentuate the Positive", "Blues in the Night", and "Hit the Road to Dreamland". The last is perhaps the echt-Mercer song – a sexy lullaby done here, typically, as a cheap comedy number. But the show hardly considers Mercer's collaborators, much less their influence on him. The song list includes no surprises, the facts of Mercer's life are presented awkwardly, and chronology is disregarded to the point of senselessness.

The misrepresentation of the Mercer sound is worst of all. Mercer wrote for older men and women with rich, deep voices and casual, self-contained sexual confidence (himself, Frank Sinatra, Pearl Bailey) or at least confidence (Bing Crosby). Rak-off, who also directs, offers four white, light-voiced youngsters, a third the age of some of his jokes. Alexandra Jay, the least objectionable, has never been worse, with moments of teeth-rotting cuteness. Female 2, as the programme gallantly terms her, is a worried-looking blonde who cheats her high notes.

One knows the show is beyond redemption from the second number, when they trip out, dresses pinned up, chirping, "Lazybones, sittin' in the shade/ How you gonna git yo' cornmeal made?" Their ostensibly comic Southern and Brooklyn accents are grotesque and at times interchangeable. The bare, unattractive set consists of white walls, a floor, and a few boxes that have all been scumbled – a fate that should befall this show as soon as possible.

To 2 February (020-7226 1916)