I agree re: Joker's handling of mental illness. On one hand, I felt that it was pretty clear that Arthur's transformation was mainly driven by social inequality but it's also very difficult to argue that the movie doesn't contribute to the cliche of "mental illness = villain".

The movie as a whole was more political than I expected it to be, actually. It was interesting to see how they tweaked Thomas Wayne's character; as far as I know, for most versions of canon, Thomas and Martha are philanthropists who spend a lot of time and money on charities, projects, hospitals, etc. But it also felt much more ... realistic? That he'd be a stuck-up rich man.