Forget the cackle or the silly Constanze, the movie is a masterpiece. As for the musicology, apart from the 'poisoning', quite sound. Milos Forman is a genius.
If you love music, Mozart in particular, try watching the great F Murray explain Mozart's Partita to the dull priest. So beautifully done, I have a hard time watching it. 'like a rusty squeezebox'
As Good As it Gets 9.5/10
Superlative acting. Doesn't get much better. I don't like Helen bossy boots Hunt, but she was fantastic in this film. Both won Best Actor/Actress.