There is no doubt that Pavarotti was one of the greatest singers in recorded history, and certainly one of the greatest that I have been fortunate enough to see in live performance. Growing up as I did in the NY area, I went to the opera quite a lot with my mother from a very early age (I saw my first opera at the Met when I was 6 years old). I still remember vividly seeing Pavarotti perform the role of Cavaradossi in Tosca. Since Tosca is such a staple of the repertory, I think I must have seen it at least 15 or 20 times since then -- and many times with famous singers cast in the title roles. I have not seen anyone who could hold a candle to Pavarotti's entrance in Act I, singing with his back to the audience, and projecting effortlessly through the huge hall at the Met as if it was nothing at all.
Pavarotti was a vocal phenomenon -- he had an unmistakable, instantly recognisable voice. He was incredibly charismatic on stage. This is NOT to say that he was compelling in his interpretations of roles -- frankly, he didn't bother acting at all, but that didn't matter. What mattered was his incredible, clear tone and seemingly effortless power. (One wonders whether what opera houses today, with their bias towards trendy new productions with costumes designed by big names from the fashion industry, would have done with Pavarotti, who grew fatter and fatter with each passing year and blatantly refused to act out roles.)
That said, Pavarotti was a singer, NOT a musician. This was a man who (if we're honest) could barely read music, and often forgot notes and words of arias he had sung hundreds of times before. This is why, when his voice started to decline, he continued to try to belt out the same old arias and (god help us) Neapolitan songs again and again, if not to his embarrassment, then to the embarrassment on his behalf of those of us who remembered what he had been able to accomplish years before. (Not to mention the lip-synching incidents, one of which led to him being "banned" from the Met roster for a period of time.) This put him in strict contrast with Domingo, a consummate musician who has used his ability, drive and intelligence to reinvent himself more than once over his very long career.
It is unfortunate that most people only know Pavarotti from the ridiculous "Three Tenors" concerts. (Calling them concerts is a stretch - they were more like one big media circus.) These concerts captured him at the end of his career, when he was well on his way to becoming a caricature of himself. Recordings from the 1970s and 1980s, such as the clip above, show him in full voice and serve his memory much better.
I did not know him personally, but in addition to the wonderful clip of him recounting embarrassing moments, I think this clip from a series of televised masterclasses in the 1970s shows him at his best. Here he is instructing a young American mezzo soprano, Suzanne Mentzer, who has gone on to have a wonderful career in her own right. As you will see, she gives an outstanding performance, which he has absolutely no trouble acknowledging. (Those of us who have performed in masterclasses before famous musicians know that the lack of ego this demonstrates is truly unusual!)