Read the reviews. Critics are mostly panning the movie cus muh soggy knees.

I mean, just read this quote from this review:

"This is a woman who is in an abusive relationship and has a deranged view of the world. Yet no one actually points this out in the film, it’s all fun when Joker and Harley Quinn are doing this. But since the film is PG-13 perhaps you might point out that this is not healthy relationship."

It's like the reviewer doesn't understand that Quinn is supposed to be a lunatic obsessed with the Joker. That's her, that's who she is, that is the character.