It's a little bit un-PC for these days so be warned. I like the animation a lot, and also I learned something about horns after watching it. Back then they would animate things even when they weren't doing anything. Nowadays Flash-animated characters don't move until they absolutely have to.
This cartoon has 2 distinct styles. There's a framing devise of a classroom to explain the actual meat of the cartoon. The classroom is done in the traditional Disney style. Then there's the musical part of the cartoon. That's my favorite part. I really like that streamlined, engineered and simplified style.
(The following has been rewritten in light of a new outlook, and so I don't appear as moronic as I did before.)
At 1st I thought John K hated this style but I was mistaken (see comments below.) John K breaks it down really well and for some reason I thought he was explaining why he hated it, but I misread it. I had no idea there was that much thought and planning going into these layouts. After I read his post and rewatched the cartoon, I do see all the imaginary construction lines.