The animation in "The Killing Joke" is inconsistent and mismatched, and I think that serves as a decent symbol for what plagues this adaptation of the classic Batman/Joker story.
It can't decide whether it wants to be a serviceable update - giving Batgirl additional agency to avoid SJW criticisms - or a slavish adaptation.
Perhaps it's hurt by the fact that it exists in a world after Christopher Nolan's superlative "The Dark Knight" explored these themes, with more intricacy and pathos for the main characters. In a sense, "The Killing Joke" is no longer impactful as it is shocking now that a masterpiece live-action film has tread and defined the territory it treads.
Also hurting it is an ending which fumbles the original work's purposeful Rorschach ambiguity.
It could have been so much more, but as it is, it's good. It lacks the impact you'd want for a story that truly highlights the depths of depravity and despair within the Joker. Though the impulse to expand the story is noble and correct for an adaptation of this sort, it just stretches in the wrong directions.