The public got its first look at the Metropolitan Museum of Art's new rooftop sculpture garden yesterday and found a bonus for art lovers.

Visitors wandered among the nine 20th-century pieces showcased in the museum's latest installation - the Iris and B. Gerald Cantor Roof Garden. Some stopped to admire David Smith's stainless steel ''Becca'' sculpture, glimmering in the sun; others posed for pictures before Louise Bourgeois's marble ''Eyes'' or tried hopelessly to interpret some of the bronze abstractions that stood boldly against the sky.

But for many, the garden, atop the 10,000 square-foot roof of the museum's Lila Acheson Wallace Wing, offered an attraction that far outshone the modern sculptures: breathtaking views of Central Park and the surrounding skyline that were ranked by some visitors as the best in Manhattan. Ah, the Scenery

''The art,'' said Rose Zimmerman, who surveyed the new addition with her ''museum pal,'' Ruth Winthrop, ''we've seen around in galleries. The scenery - that is the best art there is.''

Indeed, Michael O'Connor, a security guard who was posted on the roof yesterday, said visitors approached him often with questions, but none was about the art.

''They ask me about the bridges,'' he said. ''They say, 'Where's the George Washington Bridge?' They ask me about the buildings. They say, 'Where's the Dakota, or 'Where's the building where John Lennon got shot?' ''

Though many visitors spent much of the time gazing out over the park's emerald treetops, their backs to the art, others delighted in the whole package.

''Everyone that comes out the door takes a step back and says, 'Wow,' '' said Valerie Gladwin as she sunned herself on a bench facing the entrance to the Roof Garden. ''And I did the same thing when I walked out here. It's all so beautiful.'' Varied Works

The Roof Garden, a $2 million exhibition space that is paved with white flagstone tiles and surrounded by planters filled with Japanese yews, will be open from May 1 to Nov. 1, weather permitting. Iris and Gerald Cantor, for whom it is named, have also endowed the museum's 19th-century sculpture galleries and a special exhibition gallery. Mr. Cantor, a financier, has a renowed collection of Rodin sculptures.

The garden contains works from the Met's permanent collection: Ms. Bourgeois's ''Eyes,'' Anthony Caro's ''Odalisque'' and Eduardo Chillida's ''Silent Music.''

Other sculptures featured are Gerhard Marck's ''Oedipus and Antigone,'' Seymour Lipton's ''Catacomb,'' Jean Ipousteguy's ''David and Goliath,'' Walter Dusebery's ''Pedogna'' and Reuben Nakian's ''Garden of the Gods.''

''Eyes,'' two smooth white marble globes on a large squarish base, was an all-around favorite among those who visited the Roof Garden yesterday, with Gerhard Marck's more representational ''Oedipus and Antigone'' ranking a close second.

''You know what I think is marvelous about this whole show?'' said Blanche Josell, a sculptor who lives in Manhattan. ''Every piece is so different.

''And the views,'' she added, ''that's a whole different piece of art.''

Photo of a to the Metropolitan Museum of Art's new sculpture garden viewing Anthony Caro's ''Odalisque.'' ( The New York Times/Fred R. Conrad)