Ignaz Franz von Mosel was a student and very close friend of Salieri. In his biography of the composer, he provided the following description,

"Salieri was in stature small rather than large, neither fat nor lean, of a brunette complexion, lively eyes, black hair, temperament choleric, quick tempered, but able to say with Horace, 'tamen ut placabilis essem,' [his anger was easily appeased] for reflection always very quickly took the place of his anger. He was fond of order and neatness, dressed fashionably but always in clothes suited to his years. All games were alike indifferent to him, he drank nothing but water, but was inordinately fond of cake and sweetmeats. Reading, music and solitary walks were his favorite amusements. Ingratitude was hateful to him; on the contrary, among the pleasantest of his duties were those which a sense of obligation imposed upon him. He enjoyed doing good when he had the opportunity, and his purse was always open to those in need. He liked to talk, especially about his art, a topic on which he was inexhaustible. Sloth was disgusting, skepticism horrible to him. When he was in the wrong, he gladly confessed it; and even when in the right, if the dispute was not one touching his honor, or even that of a third person, he not infrequently, for the sake of peace, bore the appearance of being in the wrong....Usually however, he was in good spirits and full of life; his politeness, his joyous disposition, his jovial and always harmless wit made him one of the pleasantest of companions; this last quality not seldom relieved him when in a strait."  1Alexander Wheelock Thayer,
Salieri, Rival of Mozart
pg. 156.

     John Rice in his Antonio Salieri and Viennese Opera, makes the following observations,

"Salieri and Mozart were rivals, but whether the resentment and jealousy they both justifiably must have felt led them into activities that seriously damaged the other's career we do not know. Mozart and his father frequently expressed suspicion that Salieri was involved in secret machinations - "cabals" - to keep Mozart's operas off the stage or to hasten their departure. But such suspicions were a commonplace of operatic production. Salieri probably feared cabals as much as Mozart did. Joseph II was confident of the success of Les Danaïdes, but only "if there is no cabal," as he put it to Count Mercy. Da Ponte accused Casti's supporters of circulating malicious criticism of Il ricco d'un giorno that contributed to the failure and early withdrawal of Salieri's opera. Much later, in 1799, Salieri was to be prevented by an "opposing party" from taking a bow after the second performance of Falstaffone continues to sense in his [Mozart's] letters feelings of resentment and suspicion toward various members of the Italian troupe. "Italians are rascals everywhere," wrote Leopold Mozart in 1775; Wolfgang, perhaps without realizing it, inherited his father's prejudice. He seems at times to have thought of the entire Italian troupe as a cabal arrayed against him. Salieri, as the company's music director, personified the machinations that Mozart, like his father, hated and feared. "  2John A. Rice,
Antonio Salieri and Viennese Opera
chap. 14.

     Volkmar Braunbehrens provided this footnote in his Salieri: Ein Musiker im Schatten Mozarts. It involves a recent recording that recreates the incident in February of 1786 where Mozart and Salieri each wrote an opera to be performed for the Emperor and Salieri was awarded more for his efforts. Cabals, it would seem, are alive and well.

"Nikolaus Harnoncourt has produced a record of this opera [Salieri's Prima la musica e poi le parole] (Teldec) and combined it with Mozart's Der Schauspieldirektor. Unlike the care he usually gives to recordings and insists upon with the record companies, he decided not to make this a complete rendition of Salieri's work. The accompanying text refers to the fact that in Salieri's opera, "the secco recitatives as well as some of the arias [were] left out, so as to be able to get it onto one record." Apparently he was not that interested in Salieri's opera; just about half of Prima la musica e poi le parole has been cut, whereas the music of Der Schauspieldirektor is rendered in its entirety. The care given to the Salieri interpretation does not come anywhere near that given to the Mozart opera, and the recording therefore does not convey a really adequate impression of Salieri's opera. Though the apparent purpose of the recording was to reproduce both works performed on that noteworthy February 7, 1786, the real intention seems to be to show that Mozart was the greater composer. No one is likely to disagree with that, but it becomes a self-fulfilling prophecy if one does not reproduce Salieri's music in such a way that its qualities and special musical characteristics--whatever they are--can be experienced. The accompanying text does not even include a complete reprint of the libretto of Salieri's work so that one is dependent on Harnoncourt's questionable retelling of the shortened sections in order to understand what it is about."  3Volkmar Braunbehrens,
Salieri: Ein Musiker im Schatten Mozarts
pg. 241.

     Friedrich Rochlitz to Gottfried Härtel on June 9, 1822.

"Among Mozart's works he especially loved the quartets and of all the operas Figaro. 'But the concertos?' He confessed to me that, in the realm of precious thoughts completely in his style, as well as in artful and heartfelt execution, they were to perhaps to be placed at the head of all of Mozart's instrumental pieces. But, he explained, they also (and especially the last ones) exceed the style in exquisite development, and yet, given the tonally poor pianoforte, they do not serve well as concertos for today's virtuosos. 'And the requiem?' Ah, he said with solemnity, that exceeds all norms! Here is where Mozart, after a very dissipated life, and faced with his own death, was raised by a spirit of Eternity, a Holy Spirit."  4Alexander Wheelock Thayer,
Salieri, Rival of Mozart
Appendix D
pg. 168.

     Anselm Hüttenbrenner,

"Salieri did not harbor a grudge against Mozart, who eclipsed him; but whenever he spotted a weak point in Mozart he drew his students' attention to it. Thus one day, when I was alone with Salieri, he divulged that Mozart had completely misinterpreted the final scene of the first act in Titus [La Clemenza di Tito]. Rome is burning, the whole population is in revolt; the music aught to rage and be tumultuous; but Mozart chose a slow solemn tempo and rather expressed dread and horror."  5Volkmar Braunbehrens,
Salieri: Ein Musiker im Schatten Mozarts
pg. 226.

     Hüttenbrenner recorded the following comment by Salieri when he was 72,

"I feel that the end of my days are drawing near, my senses are failing me, my delight and strength in creating songs are gone; he, who was once honored by half of Europe, is forgotten; others have come and are the objects of admiration; one must give place to another. Nothing remains for me but trust in God, and the hope of an unclouded existence in the land of peace."  6Alexander Wheelock Thayer,
Salieri, Rival of Mozart
Appendix F
pg. 178.