Rockettes meet the Vienna Choir Boys;

Sweeney Todd's Music and lyrics by Stephen Sondheim. Book by Hugh Wheeler. Directed by Harold Prince. Starring Dorothy Loudon and George Hearn. Uris Theater.

"Sweeney Todd," the "musical thriller" about "the demon barber of Fleet Street," has been running on Broadway for a little more than a year. Recently, the original stars -- Len Cariou and Angela Lansbury -- retired from the cast and were replaced by George Hearn and Dorothy Loudon. Happily, these "replacements" are prodigiously talented performers, and there is every reason to believe that the show's popularity will continue to flourish on its usual extravagant level.

Miss Loudon takes a more antic perspective on her role -- that of Mrs. Lovett , who makes Todd's victims into cannibalistic meat pies. Her body sways like an reed in the emotional storms of her own scatter-brained creation, and her off-hand manner becomes still more off-handed when the most explosive matters are at stake. While Mr. Hearn stalks through the musical like a visitor from some absurdist melodrama, Miss Loudon gives a comic characterization in the most classical tradition. The combination is winning.

The rest of the cast is also on its toes, as it has to be in the wide-open spaces of the Uris Theater. This is a particularly cavernous hall; entering the second act a few moments late, I realized how far most of the spectators seem to be from even a massive production number, and even the up-front critics' seats are rather distanced from the action. It thus behooves the performers to act somewhat broadly in order to bridge this gap, and most of them manage the trick nicely.