There's no particular shame in an opera company taking operetta and tarting it up. The best houses in the world do The Merry Widow, its tale of the attempt to save the crumbling state of Pontevedro by securing the wealth of a mega-rich widow has always been popular. Welsh National Opera mark the piece's centenary with this production, but the honour done to its composer, Franz Lehar, would have been rather greater had they concerned themselves less with the title role and more with ensuring good singers in the rest of the cast.

This staging is unashamedly a vehicle for soprano Lesley Garrett - to underline the point she glides in on a troika dressed as a white Hussar to deliver the operetta's most famous aria, Vilja - and while she looked good and danced well, she deserved to be supported by better voices. Only Ailish Tynan as Valencienne passed muster, Jeffrey Black's Danilo had a certain charm but none of it vocal, while tenor Tracey Welborn's foppish Camille de Rosillon was barely audible.

The greatest failing was the deadly pace: Jeremy Sams' English version of the spoken dialogue should have been tightly nipped and tucked and, with Michal Klauza's conducting doing nothing to make amends in the musical numbers, the first two acts seemed interminable. Without the comic element of Geoffrey Dolton's Njegus, it would have been dire.

Directors Patrice Caurier and Moshe Leiser managed to put a more flamboyant stamp on the final act with the plush red nightclub decor of Chez Maxim's - its bar and mirror a respectable nod in the direction of Manet's A Bar at the Folies-Bergeres, the drawings of salacious nudes anything but. Garrett delivered the glamour element, but her voice's sparkle has faded, perhaps from singing the Pontevedrian anthem once too often. Hugh Grant was conspicious by his absence.

· Performed again on Saturday. Box office: 08700 40 2000. Then touring.