Simply Heavenly, Young Vic, London

In this musical set in a Harlem bar in the Fifties, Rhashan Stone has the lead role of Jesse B Semple ("Simple" to his friends), a good-natured factory worker whose wages seem to keep slipping through his fingers. It's no criticism of the immensely likable Stone, however, to say that one comes away from Simply Heavenly with a stronger impression of two lesser but more emphatic characters.

As Mamie, the maid who prides herself on her independence, Ruby Turner blasts with almost atomic force a follower who is not discouraged by such rebuffs as "Git outa mah face!" The suitor is Clive Rowe's Watermelon Joe, who remains confident that she will realise he is as sweet as his produce. To Mamie's initial scepticism about his seductive powers, Joe replies, with dignity: "I do not use my professional voice in your personal presence," and then does just that, turning a fruit-peddler's cry into an aria of longing and promise. When these two finally get it on, they are a hootin', hollerin', belly-bumpin' bundle of joy.

Most important of all is the invisible contributor – the director Josette Bushell-Mingo – who has made sure that each performance is sharply etched and that many are delightful. Nicola Hughes as the devil-woman Zarita keeps her elbows close to her sides at each entrance but flings her forearms apart, with a wide smile, as if opening a fur coat to show that's all she has on. When there's a lull in the action, Jason Pennycooke, as the hyperactive busboy, turns into a stray Nicholas Brother.

These triumphs of song, dance, and personality, however, are matched with words and music that are, for the most part, amiably inconsequential. Langston Hughes was perhaps the greatest American black writer of the 20th century, but he put his genius into his poetry and just a little of his talent into his plays. The plot – will Semple pull himself together and grow up before his sweet, impatient fiancée gives him the gate? – has only slightly more drama than the life of Cliff Richard, and the dialogue betrays Semple's origin as a humble-but-shrewd character in a humorous newspaper column. The lyrics, also by Hughes, are pretty basic – the entire text of "Let's Ball Awhile," in addition to the title, is "Honey chile! Sing! Shout! Beat it out!" – and David Martin's music, a combination of gospel, blues, and jive, is pleasant but predictable. The verb in that invitation, by the way, merely means "dance"; this is a milieu so genteel that a man refers to his backside as his "sit-downer."

The production, though, manages to infuse the predominantly light tone with gutsiness and grit, thanks not only to the acting but to the arrangements (by Warren Wills) and to the splendid men on piano, bass, sax and guitar. The absence of anger may seem odd, even false in this story of hardworking, low-earning Negroes, as they still call themselves (Semple sees the integration of the army as heralding a bright new day), but there is no lack of poignance and sorrow in these limited lives. At the show's low point – when one of the musicians is roughly moved along by a policeman – the company sing "Did You Ever Hear the Blues?" They leave us in no doubt that every day they hear little else.

To 12 April (020-7928 6363)