Dissenter alert:
I like Amadeus. Firstly, it puts his music up front, where it should be, and focuses on his best, most interesting work: the operas. It also treats the music in a mature way, neither succumbing to the numb hero worship of most depictions of artists, or the blandness of someone who wants to turn art into a documentary of dates and times.
Secondly, it destroys this mythological, prettified, and TOTALLY fictional image of Mozart that exists in the collective imagination of moderns as a pure medium through which divine sounds had only to whisper to be subsequently transcribed to paper with difficulty no greater than that of writing a letter. To be sure, Mozart was a talented composer, but he wrote canons called "Lick my ass good and clean", and wrote shit like "bet you can't play this part" in the margins of his horn concertos. Beethoven thought Mozart was immoral for writing Don Giovanni, and rightly so! That opera makes audiences blush to this day.
Point is he was a rude, immature, giddy young adult who was immensely talented, and ultimately whose greatest love was his craft. This is what the movie shows, and not only is it hilarious, but it's probably more accurate than how most composers are portrayed in the movies.
It also shows the distinction between wannabees and true masters, and how politics forces these mediocrities of music into positions of prominence that they don't deserve, only to have history forget them once their work is forced to stand on its own against the test of time, aside Mozart and all other suppressed masters.
If you can turn off your "nothing worthwhile is fun or funny" switch before you watch, I think you'll enjoy the movie, and also get a few things out of it.
http://www.youtube.com/watch?v=-ciFTP_KRy4