The story of Arthur Fleck, who is brilliantly portrayed by Joaquin Phoenix, is so compelling and well told it could've stood on its own. There's no need to tie it into The Clown Prince of Crime. But I get it. A movie called Arthur Fleck, no matter how good, wouldn't make more than $300 million at the box office. Call it Joker, and success is assured.
What we get is a real-world take on the classic Batman villain. This is a Joker who doesn't need to fall into a vat of chemicals to turn to evil. Here we get an already mentally ill man who can't catch a break. The harder, and crueler, his life gets, the more he descends into madness.
Phoenix and director Todd Phillips take us on a hell of ride. This is disturbing and powerful stuff that in no way glorifies the character, or what he does. If anything, it provides a glimpse into what can cause real acts of violence, and how we should NOT treat those who struggle with mental illness.
Far more schooled people than I have sounded off on Joker, so I'm gonna stop here. It's a Good, and well worth the success it received. I only wish Hollywood would've taken a chance on the story, and not the character.