In The New York Times obituary, Peter G. Davis, who reviewed a 1978 Carnegie Hall recital by Bergonzi in The Times is quoted as noting:
More than the sound of the voice, it is Mr. Bergonzi’s way of using it that is so special. He is a natural singer in that everything he does seems right and inevitable — the artful phrasing, the coloristic variety, the perfectly positioned accents, the theatrical sense of well-proportioned climaxes, the honest emotional fervor. Best of all, Mr. Bergonzi obviously uses these effects artistically because he feels them rather than intellectualizes them — a rare instinctual gift, possibly the most precious one any musician can possess.
Alan Blyth, in his Gramophone survey of Bergonzi's greatest recordings, sums up the qualities of Bergonzi's voice:
His singing there [referring to an online example], even more his earlier Verdi discs, evinces an innate feeling for shaping a line on a long breath, an exemplary clarity of diction, words placed immaculately on the tone, an authoritative use of portamento and acuti. Add to those virtues the manner by which he gives to each phrase a sense of inevitability and you say to yourself, in a mood of sheer pleasure, this is exactly how the music ought to sound. In the theatre only Otello was beyond his capabilities, though his solos are movingly sung on the Philips set.
I think I took the great man for granted. LORD!!!!!! He was one of the greatest singers in opera history!!!!!!