Mozart as portrayed is no Howard Roark, particularly because he seems to be a party animal engaged in frequent drunken sexual acts with women he barely knows.
But he is like Howard Roark as regards his artistic integrity, and that part of his portrayal was inspiring.
The overall tone of the movie is tragic, and the people around Mozart come off badly, even though they all recognized his talent.
As for the mystery aspect of the film, the "whodunit" question, the film wraps up its loose ends fairly well, and that's saying a lot considering the confusing number of story threads they had going.
I have no idea how much of the film is true. Probably it is a tissue of facts and wild speculations. I recommend it if you don't mind sitting through something dark and tragic that nonetheless honors real artistic genius.