Definitely could've been better!!! I would've removed Captain Boomerang, Killer Croc, and Katana. They are forgettable and brought nothing.
Viola Davis was tremendous as was Smith and Robbie.
Villain could've been better, too.
So, basically, you really liked half the characters and did not like half the characters and didn't like the villain. That is not a ringing endorsement.
Here are my complaints.
1). Katana. She just appears as they are getting on the plane. She is not a villain, so she does not get an explosive implanted in her neck. We get some kind of a flimsy explanation as to why she is there, but it isn't real clear. We hear 3 times about how her sword captures the souls of those she kills, but the whole concept is left completely ambiguous. Why even bring it up? I think the writer should have told us that she was there for one reason. Rick Flag's personal bodyguard. Here he is running around with a bunch of killers. He is a valuable asset and needs protections so the bad guys don't all turn against him at once.
2). Captain Boomerang. No significant back story on him. No reason to care about him. His boomerangs were basically nothing but daggers. He used them to stab creatures that attacked him or threw them at said creatures. Not once did they show that he could throw one and have it "return" to him or go around a corner and hit a hidden target. How about giving him some gadget boomerangs like one that explodes or emits light and blinds the bad guy. If you are going to name a guy Boomerang, there should be a reason he is called that. He was more like Captain Dagger.
3). K Croc. Boring. How about you tell us why he looks like that or how he got his strength/ability to stay underwater so long. Didn't it feel like the flooded the basement, where the final battle went down, just so he would have a purpose in the movie?
4, ) Waller. I thought she was great. Until she gunned down a handful of government employees who were just doing their job. that was really not needed to establish that she was a cold hearted badass. They could have done that in other ways that didn't make her deserving of her own prison sentence.
5). Why did the Enchantress have to build a machine to destroy the world? Why not use her magic to destroy the world? Machines and magic are kind of opposites, right? How about having her casting a spell that will destroy the world and they defeat her right before she completes the spell? I would expect Lex Luthor to build a machine that would destroy the world, not Enchantress.
6). Bad CGI on the machine and on Enchantress' husband.
7). Who shot down the first helicopter when they were on their way to the battle zone? The faceless monsters? Were they monsters who wanted to physically overwhelm the "heroes" or were they soldiers without faces? Because it seemed like after they were transformed, they became brutish monsters as opposed to soldiers who fought with firearms.
8). What was the point of showing us the scene where Harley jumped into the tank full of milk (or whatever it was) and the Joker went in and saved her? It was a touching scene, but what did it contribute to the story?
9). Did you really care about Rick's relationship with the chick possessed by the Enchantress? It was a huge part of the story, but it was not all that captivating. Were you guys rooting for things to work out for them? I didn't feel like they did a good job of developing either character enough that I cared if they lived or died.
