The various productions of Amadeus have received mixed reviews from the critics but overwhelmingly enthusiastic support from audiences. Peter Shaffer notes in his introduction to the play that when it opened at the National Theatre of Great Britain in November 1979, "it constituted the single greatest success enjoyed by this celebrated institution since its founding." Since its initial performance, the play's popularity has spread to Broadway, with runs of more than one thousand performances each, and several European stages. Bernard Levin, in a review for the Times (London), comments on audience response: "those who go to [Amadeus] prepared to understand what it is about will have an experience that far transcends even its considerable value as drama."

Those critics who find "considerable value'' in Amadeus include Roland Gelatt, who writes in the Saturday Review that the play "gives heartening evidence that there is still room for the play of ideas." Werner Huber and Hubert Zapt, in their article for Modern Drama, praise the structure of the play, arguing that it

can be seen as a highly sophisticated process of interpretive interaction between the stage and the audience, in which Saieri as the self-confessed murderer of Mozart is the central mediator. . . . There is a degree of thematic and structural complexity to Amadeus, which makes it, beyond its sensational popularity, a dramatic masterpiece in its own right. The play is an artistic success not only for its technical refinement (i.e., the exploitation to the full of various theatrical forms) and dramatic richness, but for the intellectual brilliance with which the theme is handled, giving the play its specifically modern appeal.

Some critics, however, find fault with Shaffer's characterization of Mozart. Robert Brustein, in the New Republic, insists that "at the same time that the central character—a second-rate kapellmeister named Antonio Salieri—is plotting against the life and reputation of a superior composer named Wolfgang Amadeus Mozart, a secondary playwright named Peter Shaffer is reducing this genius, one of the greatest artists of all time, to the level of a simpering, braying ninny." In Opera News, C. J. Gianakaris refutes those who question the truthfulness of Mozart's characterization, commenting, "Shaffer takes almost no liberties with historical fact about Mozart and his times, except where Salieri the man is concerned." Daniel R. Jones, in Comparative Drama, explains, "Mozart's animal play-acting, his word-play, his financial difficulties, his marriage to a child-like wife, and his domineering father are well documented in the biographies, Mozart's three volumes of correspondence, and in the correspondence of relatives."

Others criticize Shaffer's characterization of Salieri. In his article for Comparative Drama, Michael Hinden, for example, condemns Salieri's overwhelming pessimism as he "abandons his quest for union with divinity and becomes the antagonist of God, setting himself against the Deity in personal confrontation and defiance." Benedict Nightingale, in his review for the New Statesman, complains of Salieri's "implausibility." He comments that Salieri

is thought to have schemed to Mozart's disadvantage, and, in his senility, is said to have claimed to have poisoned him. From these hints and rumours Shaffer manufactures a blend of Iago and Faust, much at odds with the historical Salieri, whose conventional efforts were as triumphant as Mozart's musical adventures were neglected, and therefore had no motive for murder.

Amadeus won five Tonys for its New York performances, including a Tony for best drama of the 1980 season. The popularity of the play ensured the success of the 1984 film version, which received nominations for eleven Oscars, winning eight including best picture, best director, and best actor.