Personally I feel like the review have been harsh maybe 5.5/10 as opposed to 3/10 that being said I think that a director's cut could do wonders for this movie.
One of the biggest downfalls of this movie was the marketing, making it appear as if The Joker was the main antagonist of the movie whereas he had a very small role and almost all of his scenes were already shown in the trailers.
One thing I did like about the movie was the characters, Deadshot and Harley Quinn were portrayed well though that may be because they were given much more screen time than the others. I loved Captain Boomerang which seems to be an unpopular opinion. As for Jared Leto's Joker, I think it's too soon to tell, he doesn't really get enough time in the movie to be able to tell what he'll end up being like. I'm neutral on Diablo, didn't hate him didn't love him. Killer Croc and Katana weren't given enough time to be fully appreciated. Enchantress was good towards the beginning but gradually fell farther and farther.