Well,we all saw age of ultron and that's a film that was butchered by the studio. So joss couldn't do much when the studio took control.From someone who saw it..
Slow-mo: I don't mind slow-mo, but I do find it might have been used a tad too much or there were scenes where it was a bit unnecessary. You'll probably understand when you see it.
He did give it a 9/10 though
With Joss helping edit the final cut, i think it'll help a lot since that's one of Zack's weaknesses. A lot of films are made or destroyed in the editing room
Zach's director cuts have always been vastly better than the theatrical versions. That tells you the problem isn't really with him but the studio.
That's on wb I'd say,and again,joss had the same problem with ultron. Ultimately the editing will live and die on wb execs.
If the film needs to be longer than 2 and a half hours,than that's what it needs to be. Once you start cutting stuff out only because you want more money from more theatre showings that's a problem.
I do wonder how much different the reaction to bvs would be if the ultimate cut was the one shown in theatres.