Sizing up the Met's up-and-down season so far

After a disastrous opening week, the Metropolitan Opera pulled itself together for a strong ''Frau Ohne Schatten,'' and, in truth, the opera season had finally begun. Since then it has had ups and downs (including a 'La Boheme' reviewed on these pages Thursday, Dec. 24).

There is a long list of singers who do not appear with any regularity at the Met. But there is a solid list of important talents who do, and several evenings of unalloyed pleasure are to be had from some of them. The most impressive was the pairing of Mariella Devia and Matteo Manuguerra in Verdi's ''Rigoletto,'' a truly golden-age partnership.

His is one of the great Rigolettos of the day, alertly acted and sung on a grand scale, communicating passions and fears on a rich flow of expertly controlled and nuanced sound. Miss Devia is on the verge of a brilliant career. The voice is bright, full, and strong from top to bottom. She is just the sort of vocal exhibition that makes its dramatic point while inciting an audience to near-riotous ovations). Her coloratura is bold, clean. Her only shortcoming at this early point in her international career is a proclivity to emotional reticence, though that is perfectly valid in this opera.

Renato Bruson offered an ideal Germont pere. Every histrionic point was made with skill, taste, and control. The voice is a genuine Verdi baritone, though it tends slightly to the muffled and nasal in the upper reaches, so that rather than swell into climactic phrases, they are forced. But this is a small quibble for a performer of such obvious theatrical gifts.

Renata Scotto had a particular triumph when she first attempted the three heroines in Puccini's ''Il Trittico'' a few seasons back. Her recent portrayals still carry the histrionic impact of her tour-de-force outing. The ''Tabarro'' Giorgietta is all smouldering passion. Her ''Suor Angelica'' heroine remains uniquely touching in something that usually invites hysterical excesses. Only her Lauretta in ''Gianni Schicchi'' lacks the freshness of yore. In fact freshness and vocal luxuriance are no longer a part of her voice, so audible is the effect of those dramatic roles she should never have attempted in the first place.

In this run, Bianca Berini was a good Frugola and an adequate Princess; Jocelyn Taillon was a dour, unamusing Zita. Later, Miss Taillon showed no compatibility at all with the Princess - a far cry from the days when a past-her-prime Fedora Barbieri proved superb, and Lilli Chookasian packed quite a wallop (as she did this season as Frugola - here is an artist unjustly ignored by the Met). Gabriel Bacquier offered just the sort of enchanting, charming Schicchi one expects from this master performer, as did Italo Tajo as Simone.

One ''Tosca'' reached a good level of dramatic tension, thanks to Carol Neblett's vastly improved portrayal of the title role. Sherrill Milnes's very macho Scarpia had moments of raw terror. Jose Carreras was in decent voice, although the signs of his vocal deterioration through misuse are shocking in one still so young. Giuseppe Patane was the tempestuous maestro who galvanized this performance the way he could not when the cast included the peculiarly tepid Miss Zylis-Gara in the title role, the honorable if dull Louis Quilico as Scarpia, and the authentic, poetic, ringing Cavaradossi of Giuseppe Giacomini.

In the second ''Frau'' cast, Eva Marton repeated her impressive Empress, Gerd Brenneis and Franz Ferdinand Nentwig were again weak in their respective roles. Gwynn Cornell gave a confident, attentive, effective account of the potentially troublesome Nurse. The voice rang true and clear, and she had imaginative ideas about the character.

Brenda Roberts as the Dyer's Wife (Birgit Nilsson's role this season), began strongly and then became erratic vocally. Dramatically, she presents a dowdy slattern, giving no hint of the tragic dimensions implicit in the text.

In the current revival of Mozart's ''Die Zauberflote,'' one could cite Kathleen Battle's delectable but conspicuously small-scale account of Pamina (which until recently was the province of heftier voices, not light soubrettes), as a high point, along with Thomas Allen's ingratiating Papageno. Martti cqTalvela was in fine, resonant voice as the sepulchral Sarastro. David Kuebler was a handsome, vocally acceptable Tamino, Zdzislawacq Donat the erratic Queen of the Night, Michael Best an unfortunate Monostatos, and Allan Monk an impressive High Priest.

On a level lower than this were such performances as Cornell MacNeil's sour-voiced Michele in ''Tabarro,'' Giuliano Cianella's insecure (though well-acted) Rinuccio in ''Schicchi,'' and Dano Raffanti's tenuous Alfredo in ''La Traviata,'' where the often-excellent Catherine Malfitano proved over-parted, vocally colorless, with a penchant to frantic overacting in a role that will never really suit her (startlingly contrasted with the nearly still yet dominating Mr. Bruson). On the downright poor side there were such things as Carlos Montane's diminutive, sour-toned Duke (''Rigoletto''), Gilda Cruz-Romo's sloppy, squally ''Angelica,'' and Galina Savova's matronly Giorgietta.

The conducting has ranged from Lawrence Foster's dully routine ''Zauberflote, '' and Nicola Rescigno's listless ''Traviata,'' to Patane's alert ''Rigoletto,'' James Levine's marvelous ''Trittico'' and newcomer Angelo Campori's idiomatic, thrilling ''Trittico,'' which he took over from Levine after the telecast).

Dramatically, a strong hand is still lacking to control the personal excesses of the Cruz-Romos and the Malfitanos, and to bring out the personalities in the Savovas, or Robertses. But overall, the Met is chugging along, even if on a more placid level than the art form it showcases nightly should be.