It turns out that Pyotr Ilyich Tchaikovsky did not like his epic 1812 Ouverture. Here is what I read in Wiki:
"Meanwhile, Tchaikovsky complained to his patron Nadezhda von Meck that he was "not a concocter of festival pieces," and that the Overture would be "showy and noisy, but [without] artistic merit, because I wrote it without warmth and without love," adding himself to the legion of artists who from time to time have castigated their own work"
I am not sure how should I interpret this. Umberto Eco said once that he does not give a damn about the relation between writer's life and the book itself. I guess I'll stick with that, whatever this Genius said about his piece, I still believe it is brilliant. Perhaps you gotta have the ears of a genius to make such a comment.
The last movement from the overture has long taken its top place in my personal the best fitness music list.