Looked back at Disney's Fantasia for the first time since I was six. It's still rubbish.
Sir we shall have words over this. Fantasia is probably the most amazing project Disney ever produced.
Challenge accepted 
What exactly did you like about it?
Pretty much everything. It's probably the purest example of flat-out animation that Walt Disney ever produced, and its format allowed for far more creative freedom than the standard big musical movie or Mickey Mouse short (not that there's anything bad about those, but they wind up being a lot of the same thing). Tying the pieces to classical compositions lent a real sense of timelessness to it. "Night on Bald Mountain" is one of my all-time favorite animated pieces ever...hell, in what other Disney work can you see topless demon women?
As a general fan of animation, I absolutely love it when animators are able to cut loose and strut their stuff, and that's Fantasia in a nutshell.
I'll concede that the animation was high quality, and the classical music well-selected. My problem with the movie was... inconsistency. I like classical music, and I've got nothing against disney cartoons, but Fantasia tried to fuse a very long music concert with an extremely long cartoon marathon. This leads, IMHO, to something of an identity crisis, or more accurately a target audience crisis. Kids who want to see Mickey Mouse cartoons will simply fall asleep; adults who want to hear some classical music will usually find at least some of the cartoon sequences annoying (the centaur one especially). If it works for you, all well and good, but it didn't work for me. If I want to hear classical music I go to a proper concert (to be fair, not everyone is lucky enough to have a great concert hall just a few hours away)
Regarding the Bald Hill/Ave Maria sequence... here's the thing. It's a really good sequence. The animation is spectacular, it fits the music better than any other part of Fantasia. I STILL find it frightening today,
more so than most zombie or slasher films. And the conclusion, where the horrifying beast is driven off by the sound of church bells and the procession of simple villagers, is very poignant. It would have been great if had been released as a standalone short film.
Here's the problem. It's not. For one thing, You have to sit through two hours of, well, the rest of Fantasia to get to it. But much more troublesome is the fact that Bald Hill/Ave Maria is orders of magnitude more intense than the rest of the film. Fantasia is (ostensibly) supposed to be a kid's film, or at least a film young kids watch. BH/AV is NOT a young kid's cartoon. Once again, a sort of identity crisis. Sticking Mickey Mouse and
CHERNOBOG in the same film strikes me as foolish; sticking Mickey on the cover and providing no warning about
CHERNOBOG makes it feel like a cruel joke.