Noooooo! I really did not need to see that! X( You've just traumatised me for life. :( That was just cruel.

Personally, I think they're terrible. They end in the middle of the 2nd book. I saw them before the Jackson LOTR, so my opinion would be better than most people.
Bakshi is talented, but he was underfunded for this one (and most of his career) and it was clearly rushed. Too bad Cool World more or less killed his career.
If you like Music, you owe it to yourself to see American Pop. Brilliant movie. IMO, his best. Fire and Ice wasn't bad either in a good b-movie kind of way, but I think American Pop was the only movie he did that qualified as art.
Personally I don't like his other stuff e.g. Fritz the Cat, etc. It's all mildly amusing, but the animation is awful. He can't plot either. That annoys me.
edit: American Pop is on Crackle (country-limited) if you want to watch it free.