Has some nice elements, but ultimately feels pretty thrown together, with sudden tonal changes, first 30-35 min is just introducing who people are, and really I just didn't care about anyone outside of Diablo. Overstuffed, too. No reason for Katana to be in there. Like, at all. No idea why she would be on the team either, given her backstory, mindset, and their explanation for her being there is "this is Katana". She does nothing and just balloons the cast.
Leto is just playing a sociopathic gang leader. If it wasn't for the Joker dressing, you wouldn't have thought Joker at all. I also dont think Harleen would have become obsessed with this version of the Joker at all. He has zero charisma or manipulation skills, or anything like that. He's just a dude with face paint that you wouldn't wanna deal with cause he'd probly fuck you over in one way or another.
Biggest strength is the art department, they had some cool looking visuals and effects in there. Especially one point near the end where 2 characters are going at it while being cheered on by the rest of the squad.
Edit: Throughout the first half they shove in a ton of songs, upbeat classic rock and whatnot. Same tone as the trailers, and it just doesn't fit. Feels very shoehorned in.