Messy structure. The entire "Joker's coming for Harley" plotline goes nowhere and does nothing. Weird problems with tonality -- sometimes it's dark fun and other times it's straight-up unpleasant. The team never really jells enough for me to buy that Diablo has just started thinking of them as his second "family." Problems with focus -- if this is an "Anti-hero Avengers" team-up movie, why is there not more focus on characters other than Deadshot and Harley? Points for doing Batman well in his few scenes. Wish the female characters hadn't been so objectified. Problems with editing -- it seems like there were scenes where something was going on between Harley and Deadshot but they got cut, and its portrayal of what should have been depicted as an abusive relationship between Harley and Joker as somehow real love is... an unsettling creative decision. I can't really tell if Cara Delevigne's performance is mediocre because of her abilities as an actor or because of the limits of the material she was given, but she underwhelms -- points for trying to do something really nifty with the Enchantress's physicality as an embodiment of the character's wild, primal nature. I do wonder what David Ayer's version would have looked like without studio meddling. But, it manages at least to be entertaining (which is more than Batman v. Superman could say for itself) by sheer virtue of Margot Robbie, Will Smith, and Viola Davis carrying this film on their backs, but it never quite reaches the lofty status of "actually good."
Bob Chipman ("MovieBob") called Suicide Squad "the radio edit of a Kid Rock cover of a Iggy Pop track; the feature-length adaptation of a blonde, mullet-sporting ten-year-old shouting 'Worldstar!' from the Chuck-E-Cheese ballpit on Snapchat."
Sounds about right to me.
Final score: C+ for the cast.