Promises, Promises--You might prefer to listen to the original cast album instead of going to the show, but the Burt Bachrach-Hal David score to this musical version of "The Apartment" is something to be heard. If you attend the show, beware of the unfortunate Neil Simon book. At the SCHUBERT, W. 44th St. (246-5990).

Repertory Theatre of Lincoln Center--Two interesting, if not great, productions--Lee J. Cobb in director Gerald Freedman's "King Lear" and Frank Langella and Anne Bancroft as the Shakespeares in William Gibson's new "Cry of Players." At the VIVIAN BEAUMONT, W. 65th St. (362-7616).

Sweet Eros and Witness--Two one-acters by Terrence McNally, notable for their spasmodic blasts of humor and the most extended nude sequence to date to appear on a New York stage. At the GRAMERCY ARTS, 138 E. 27th St. (OR 9-7665).

Tea Party and The Basement--Harold Pinter's latest and up to snuff. A capable cast includes Valerie French. At the EASTSIDE PLAYHOUSE, E. 74th St. (UN 1-2288).

We Bombed in New Haven--Joseph Heller's anti-war play, that, while no "Catch-22," has nice moments all the same. With Diana Sands and Jason Richards. Closes Dec. 29. At the AMBASSADOR, W. 49th St. (265-1855).

Zorba--A great serious musical about living, loving, suffering and dying. John Kander and Fred Ebb wrote the immensely theatrical score; Joseph Stein did the book; and producer-director Harold Prince tied it all together with a finesse the likes of which have not been seen since Jerome Robbins' heyday. Herschel Bernardi and Maria Karnilova are the leads, with a strong assist from gutsy-voiced Lorraine Serabian, who heads a Greek chorus. At the IMPERIAL, W. 45th St. (265-2412).