It'll be terrible. They have already tried damage control by saying it's not a comic book movie and it's not actually The Joker but rather a character who is sort of is but isn't the joker. Also with movies now getting banned for targeting wealthy elites then this will end up getting pulled which night actually make it sell well on blu ray as the film they didn't want you to see.
It's basically Sonic, remove the controversy and it's still destined to be gooseberry fool. Joker, much like Alien, Predator, Venom should all have a mystery to them. Everytime they try to explain the mystery it goes poorly.