There is basically two version of this movie badly cut together. Remember those rumours of reshoots to add humour that was shot down? Turns out is true because you can see an obvious tonal shift from the second arc onwards.
Performances from the casts are a mixed bag. The stand out would be Margot Robbie as Harley. She is an eye candy and understands the character very well. Will Smith, well, he is the doing the Will Smith thing. Is not a breakout performance of any kind. Is just Will Smith. Captain Boomerang is the comic relief, to the point that his character is a caricature. I am not sure if that is how the character should be cause the Captain Boomerang in Arrow is like miles better. El Diablo has some surprisingly heartfelt scene and reserved performance. Rick Flagg is your generic GI with a predictable character arc. Killer Croc and Katana are as cookie cutter as it gets and has basically zero character development. Don't even get me started on Slipknot. He is the first to die and in an extremely pointless scene that almost feels insulting. In a nutshell, David Ayer is not the right guy for this. He can't handle an ensemble movie and it shows. There is very little chemistry with the whole squad.
Enchantress turns out to be the main villain as I suspected and kudos to them for hidden the other villain so well though ultimately, is also another generic villain. Viola Davis is a great Amanda Waller but she doesn't really have much to do here beyond acting intimidating. She will be a good character that has constant presences in all DCU ala Nick Fury though.
For a supposedly major entry into the DCU, Suicide Squad doesn't actually feels like a big budget movie. Remove the DC branding and their characters and it would have been a generic B-grade movie about a ragtag bunch on a mission. The fire CGI for El Diablo is just horrendous. Is some of the worse I have ever seen. Most of the time, it looks like something out of a PS2 era videogame.
The action scenes are also horribly shot like most modern movies these days. Too much closeups, too much cuts, and the overall dark cinematography does not help convey any clear action scenes. Half the time, you are wondering who is fighting who. These are worse than Nolan fight scenes. Say what we want about Snyder but that man knows how to do clear and concise fight scenes.
The soundtrack is easily the one of the weakest aspect of the movie. It is scored like a Tarantino film, i.e. using famous songs but it doesn't fit well in this movie at all. There is no consistency to the choice of songs and I get that they are trying to show that these are a bunch of individuals that could not be more different from each other but it is really jarring each time a different song comes up. GoTG did it perfectly well with this formula. SS sounds like a bad mix tape.
And the Joker, after all that hype and also BTS shenanigans by Jared Leto, his Joker can be summed up with one word, generic. Strip off his green hair an pale makeup and he is just another generic psychopathic villain. Suffice to say, his Joker will go down as the weakest one yet for a live action depiction. This is not the case of Ledger setting the bar to high, this is more of a case of someone not really getting the character at all. There is an element of self consciousness to this Joker. Like Leto himself feels silly playing this role. The result is a half baked portrayal of one of the greatest villains of all time.
DC is currently at a crossroads. They need to either go all serious or go light. This hybrid half dark/half comedy approach is not working at all.
and 2 of them could count as "classic" 
