William, Paul.
Strange enough, "Amadeus" and "Shakespeare in love" are amongst the films I liked most in my whole life.
It can be personal, but I found those are great films (good story, good actors, good screenplay, good everything in fact).
When it comes to historical faith, it is my belief that historical books written by historians are just that : books written by people (like the bible, you know). In the few cases we have documents first hand written by the protagonists themselves, well, those documents are just that : documents written by protagonists. In no case those documents seem to me more valuable in term or "truth" than what an artist can "feel" about what the truth has really been. If you were to write a book about your life, what would you do ? If you wrote a book about a friend of yours that you like, what ? one you don't like, what ? If you were asked to write the comments on the back of a record of a composer you like, what ? No hard truth, anyway. Is the truth about Mozart in his letters to his father ? Then indeed, he would appear a miserable man.
If I said what I feel : while I adore some of Mozart music (I like his mass music more than his keyboard music), I find that his writing is sometimes, well, a bit easy, largely copied upon the italians of his time and not elaborated like say that of Beethoven (which by the way I like less). Think of how conservative his writing tricks are, think of how short his developments are, think of how poor his orchestration skills are, all this not whistandig his evident genie, of course. I can hear you say "bullshit, man" while it could really be like I said, it is just that this is not what the critical mass of amateurs think about Mozart. Because Mozart is not a human being anymore : he is a legend. No truth applies to a legend.