She is nothing but a comic relief overall, including her first appearance in the animated series.
But her origin story showed us that Harleen is a psychologist who got sympathized to the Joker, which gave her a lot of potential and could give her character depth, but most of the time Harley Quinn showed nothing resemble to the character.
The Harleen issue further expanded the story and made her very tragic figure, but I feel that doesn't have anything to do with the actual Harley.