Just come back from the movie myself (got off to a late start here in Germany). It's a fun film, but it's also most definitely the weakest of the three DCEU movies to date.
Going back through the DCEU, I'm undecided as to whether I liked MoS or BvS more - both were excellent movies (referring to BvS in the Ultimate Edition here - the theatrical cut of BvS was good but very cluttered, and going back to it from the Ultimate Edition makes the theatrical cut look like a train wreck). MoS was very much in the mould of Nolan's Dark Knight trilogy, but BvS was definitely Synder's baby through and through with a much stronger Watchmen vibe to it.
It's hard to place what Suicide Squad is trying to be. It felt like it was trying to be a dark version of GotG in many places. There were accusations that WB hit the panic button and tried to make the movie more "fun" with reshoots and the like, but it was surprisingly light on humour. It had a remarkably uneven tone to it. I could see where some of the reshoots had been done as there were a number of scenes that were obviously reshot from the trailer with different lighting and framing.
But the retro pop & rock music seemed unnecessarily tacked on and in many places overbearing. In fact, I had the distinct impression that they were trying to cram as much of the soundtrack in as they could to compete with GotG. On that note, they should fire the sound editor because, honestly, the soundtrack was so overbearing for much of the film that you could often not hear the dialogue properly.
** Here be mild spoilers **
I also wish they'd left more time for the origins, as the start and the end of the movie were the most interesting parts. The clips of Batman and the Flash catching the various villains felt so horribly rushed that I was left wanting more. The hunt through Midway City that made up most of the second act was painfully dull, the "twist" was a damp squib, and it wasn't until El Diablo comes into the fold more that the interest factor perks up again.
A lot's been made of Jared Leto's minimal screen time, but honestly, I felt he was on screen enough and instrumental enough to the story to be worth including. I also felt he was just fine in the role. Ledger's Joker was always going to overshadow him but I found that he was different and interesting enough from the Hamill/Baker/Romero/Nicholson/Ledger Jokers. I liked the way they played out the Joker/Harley scenario as a toxic romance in the vein of Bonnie and Clyde.
As for the others, everyone's casting was pretty much spot-on. Margot Robbie is going to be the definitive Harley for a while yet I think. My thoughts on Will Smith's Deadshot are below. Jai Courtney was great as Captain Boomerang, spot-on comic timing. Katana, Killer Croc, Rick Flag all good, but very little screen time to really make a proper judgment.
Breja: He wasn't an enitrely joyless character either. And trust me, Smith isn't goofing around in the role. I really think they pretty much nailed Deadshot. He might be a bit nicer than he was in Secret Six (pretty much the only comic book series I really know him from), but then again the whole movie isn't going for quite that deranged and messed up tone. The only thing that bugged me a little was how he barely ever wears the mask. I guesseither SMith didn't like it, or the producers didn't want to hide their main star. Still, it's a minor point, and they made the character really work.
Deadshot's a very malleable character though who seems to change so much on a regular basis, only keeping a few common traits, so any actor could basically play themselves and still nail Deadshot. But yes, Smith was great in the role. Balanced out the comedy with the emotional aspects very well.
