WASHINGTON OPERA'S new version of "The Merry Widow" -- Franz Lehar's matchless celebration of high life and true love among the priviliged of pre- Great War Europe -- is a feast of visual and vocal opulence.

In its finest moments, the production, which opened Monday at the Kennedy Center Opera House, is more operatic than operetta-ic. But that's just fine.

Stars Mary Jane Johnson and Richard Stilwell are first and foremost opera singers, solidly bearing comparison with previous operatic exponents of widow Hanna and her lovesick- but-proud former lover, Count Danilo.

This on-again, off-again and on once-again romance is a classic of turn-of-the-century romantic wish-fulfullment. Unlike most such works, it benefits from operatic intensity.

With Johnson, Hanna's "Vilja," perhaps the most famous single solo segment from any operetta, is not just a song, but an aria. Johnson took her time, building its opening, refrain and epilogue with considerable sensitivity. Johnson's voice is almost ideal for the music, consistently resonant at every level. There's just enough of an edge for it to project without seeming effort; she has an individual timbre that immediately registers. Her characterization of the widow whose inherited 20 million francs could save her little Balkan country is less regal than many, but it's supported by the script: She's a farmer's daughter.

Stilwell's Danilo is perhaps the finest of the many things he has done here over the years. One of the great appeals of this splendid character is the underlying rage that gradually breaks through the years of accumulated pride and frustration as the relationship with Hanna is renewed. When it surfaces, for instance, in the tale about the estranged prince and princess at the end of Act II, Stilwell projects a most unoperetta-ish intensity. All is sung wih the clarity of a seasoned recital artist, and acted with the dapper assurance of an experienced stage performer.

The secondary lovers -- Valencienne, the Balkan ambassador's wife, and the Frenchman Rosillon -- are appealing as sung by Wendy White and David Kuebler. And if they seem subordinate, that's in Lehar's vocal scheme of things. In the speaking part, Baron Zeta, the Ambassador from Pontevedro, Donald Adams is full of spirit and expert timing.

If only the direction had brought about more of the same elsewhere. In the opening, those entrances down a grand staircase to the embassy party drag on and on. By the time Hanna makes her grand entrance (in an unbecoming gown), she almost seems just another partygoer. The pacing of the spoken sections, under director Peter Mark Schifter, needs to be tightened (the production is in English).

Conductor Cal Stewart Kellogg, also, was slow at unbending into the mellow orchestral timbres and flexible phrasing that help such passages along. By Act III, though, he had captured the Lehar manner.

Zack Brown's sets and costumes are brilliant. He places us in Art Nouveau Paris, full of extravangant curvilinear objects, from candelabra to a Tiffany-style outdoor pavilion, all muted by pervasive dark green, blue and purple. And Baayork Lee's choreography is full of life, especially a can-can in blazing red to top off Hanna's house party.

This "Merry Widow" has all the glitter that last spring's version by the Vienna Volksoper lacked. With a little more work, it might also develop the Volksoper's stylistic authority. THE MERRY WIDOW -- This Saturday and November 13, 16, 21 and 25 at the Kennedy Center.