George Gershwin's classic opera, Porgy and Bess, has finally come to Boston (it opens today at the Astor), heralding, it claims, "a new era in motion pictures." This may be something of an overstatement; but let it be said here and now that Porgy is a mammoth, melliflous hit!

This simple tale of a kindly cripple who falls in love with the neighborhood tough's mistress had its world premiere in Boston twenty-four years ago, to critical acclaim but only moderate public support. After Gershwin's untimely death in 1937, it was successfully revived on on Broadway by Cheryl Crawford in 1942, with the important addition of occasional dialogue. In this more popular operetta form, it has since become a part of our musical heritage and an international box-office success.

Now, after ten years of preparation and two years of actual production, Samuel Goldwyn has brought it to the screen in Technicolor, Todd-AO, and stereophonic sound, where it will probably enjoy more box-office success than ever.

N. Richard Nash, a major Broadway playwright, has fashioned an excellent screenplay, remarkably faithful to DuBose Heyward's libretto. And Oliver Smith has captured the flavor of Catfish Row in an authentic-looking, yet properly stylized set. The color, the lighting, Irene Sharaff's costumes--all beautiful. Andre Previn (winner of last year's Academy Award for his work on Gigi) did the arrangements, which bring a new fullness to the Gershwin score. They are lush in the best Hollywood tradition, but never maudlin.

Without gifted performers, however, it would be all for naught. Mr. Goldwyn has fortunately secured the services of Robert McPherrin and Adele Addison to sing the title roles and some of the top stars in the business to do the acting honors.

Sidney Poitier is superb as Porgy! His performance is certain to win him another Academy Award nomination, and he may well walk away with it this time. Mr. Poitier has always been commended for his sensitivity; but in his Porgy we see a new dimension for it, for this is the first time, to my recollection, that he has been cast in a truly gentle role.

Ruth Attaway, as Serena, provides one of the most moving and memorable moments in the film. She does not actually sing "My Man is Gone Now,'" but she acts the hell out of it, and frankly it is often hard to believe that she isn't singing, the voice fits her so well.

Sammy Davis, Jr. is a slick, quicksilver Sporting Life, and his renderings of "It Ain't Necessarily So" and "There's a Boat That's Leaving Soon for New York" could not be topped. Pearl Bailey is on hand as Maria, and one only wishes that her part were fatter.

Diahann Carroll makes a lovely thing out of Clara. It is only unfortunate that she was not allowed to sing for herself, for her rendition of "Summertime" in her own album of the show's music is much more exciting than the dubbed version in the film.

Brock Peters is a striking Crown, with a rich, thunderous baritone voice. And Helen Thigpen makes a particularly memorable moment out of the Strawberry Woman.

Only Dorothy Dandridge, looking radiantly beautiful, seems to be not quite up to her dramatic chores. This is certainly her best performance to date; but, though she has captured the fierceness and passion of the woman, there is something missing of the warmth and sincerity of Bess.

Mr. Goldwyn has successfully preserved the atmosphere of poverty in a South Carolina slum without making it tiresomely realistic or stereotypical. The result is 136 minutes of powerful theatre. This is undoubtedly the most successful adaptation to date of a stage musical to the screen.