In "La cantata del santo bevitore", Angelo Folletto wrote:

[...] the opera with its private grief ("sono un povero uomo che soffre e ha sempre pianto da solo - I am a poor man who suffers and has always wept alone" sings Sly in the final tragic self-portrait) comes alive, above all, in the strength given to the portrayal of the 'defeated' protagonist. As in 1998 in Zurich, where this production was born [...] José Carreras who has regained his declamatory powers and conveyed powerful emotion, even if he was a bit 'sparing' with his vocal coloring hit the mark as the protagonist.

In "Carreras un poeta inaugura il Regio", Armando Caruso wrote:

[...] Undoubtedly all merit goes to the Teatro Regio and to José Carreras in this version of the "Legend of the Sleeper Awakened". They have opened the archives of 20th century opera and returned it to the stage, and in this case, with a protagonist worthy of all respect: José Carreras, who had been absent from the Regio for a decade and now re-appears at the height of an interpretive maturity that merits great attention. [...] And it is in his moving from one state of mind to another that one can admire the artistry of Jose Carreras, an intelligent artist, cultured and sensitive, admired around the world, who has triumphantly brought Sly to Barcelona and Zurich. [...]

In "Quando la lirica si fa teatro: Carreras convince con Sly", Paolo Isotta wrote:

[...] The pivot of the drama and also of the music is the tenor José Carreras. Few can act like he can: few know how to say so much with only a movement of the eyes or a simple gesture. If of Tamino the Priest [a reference to Mozart's Magic Flute] one could say "He is more than a prince, he is a man", of Carreras we can definitely say that he is more than a tenor, he is a personality. That there may be others who can sing better than him matters little. What younger tenor possesses a diction so clear and so touching, in fact, as one maestro has described it, such a perfectly articulated sound that in his pronunciation the words and the music are as one? [...]