By now it has become reasonably clear that many fans didn't respond well to Suicide Squad. Despite some excellent trailers and a ton of social media chatter leading up to its August 2016 release, the film was widely panned by many critics and considered a weak spot in the DCEU canon. That said, Suicide Squad star Margot Robbie apparently went into the divisive David Ayer project fully-aware that it wouldn't meet every fan's expectations. As the I, Tonya star put it:
I think when it comes to something that has such a huge fan base already obviously you want to do the fans justice, you want to show them the characters that they fell in love with, but you also can't be paralyzed by the idea that you can't please everyone.
Suicide Squad was packed to the brim with classic DC characters like Harley Quinn, The Joker (Jared Leto), Captain Boomerang (Jai Courtney), and Deadshot (Will Smith). Even with Margot Robbie's fairly comic book-accurate portrayal of the character, the film altered quite a few aspects of her origin story and personality that weren't entirely in-line with the version of the character introduced back in Batman: The Animated Series. Per her Robbie's remarks to MTV News, she wanted to please fans of the character with the Task Force X movie, but she also didn't want to let that stop her from taking creative liberties whenever appropriate. In that regard, the film was always going to rub a particular segment of the fanbase the wrong way.
Of course, on the other side of that argument, it's worth noting that the characters weren't necessarily Suicide Squad's biggest issue. The core story was subject to many reshoots and drastic edits over the course of the film's production, which arguably left fan-favorite characters like Harley with poorly-defined roles in the overall story. In fact, Robbie's portrayal of Harley was one aspect of the film that actually did seem to generally please fans.
It's also definitely worth mentioning that the criticism that Suicide Squad received doesn't seem to have discouraged Margot Robbie from sticking with her role as Harley Quinn for the foreseeable future. The actress reportedly remains attached to the recently announced Joker and Harley Quinn movie, and Suicide Squad 2, as well as David Ayer's Gotham City Sirens movie -- although we haven't heard much about those projects recently. Beyond that, it was also recently revealed that Robbie has been quietly working on a Harley-centric solo film. She has made it clear that she's interested in returning to the role very soon, so we will just have to wait and see how the character (and the audience reception to her films) continues to evolve.