Sweeney Todd is a Sondheim masterpiece, the story that inspired him to look unflinchingly at the pleasure people take in cruelty. John Doyle's production, which arrives on Broadway with an American cast after a London engagement originally staged by the Watermill Theatre, brings out the horror and desperation better than any I've seen. In approach it is ingenious. Yet in performance I found it oddly short of the chills that a singer's note perfectly placed or an actor's line wonderfully wrung can provoke in an audience.

The disappointment is minor, since Sweeney is one of those scores I could listen to once a month and still find new colours and harmonies. Here the musical rewards are especially rich: Sarah Travis reduced and re-orchestrated the music to fit 10 players instead of the original Broadway production's 27, and the resulting textures are phenomenally spooky.

That the players also happen to be the actors onstage - enacting the tale of a Victorian barber, in league with the meat-pie- producing Mrs Lovett, bent on revenge against the judge who wrested wife and daughter from him - makes the evening novel. The second act especially unfolds with extraordinary seamlessness.

And yet I was so frequently aware of the wheels turning that I had trouble surrendering to the staging. Finding young performers to play instruments as well as the roles of sailor Anthony and cloistered beauty Johanna must have been a challenge: what was gained in versatility is lost in vocal beauty.

Praise has been justly lavished on the production's two leads and its look: the raven bob of Patti LuPone's Mrs Lovett and the German expressionist - or, rather, young von Stroheim - smooth pate of Michael Cerveris's Sweeney. The dark coffin placed centre stage can be suggestive, especially when it is used to enact human butchery: crime's sacrificial altar. But this account of Sweeney is more enjoyable than entrancing.