Saw it yesterday! It certainly wasn't terrible, but nothing stellar here. The biggest problem I think this movie had was runtime and lineation. 2 and a half hours is a little excessive for a movie that isn't based off of a J.R.R. Tolkien book, imo. It seems like Zack Snyder likes to run his superhero movies on the long side, and I haven't really seen that pay off yet. Writers seemed to have been dealt a bad hand here, trying to bridge together two monumental characters with their own stories and reason for not liking each other. The result was a big sloppy mess, and forced them to gloss over a lot of the other characters that weren't superheroes or villains.
Despite the mess of trying to make two stories conjoin into one story, as I said, there are some things that could definitely have been cut to keep things chugging along. The little Rocky-style workout scene with Batman and the "public perception" scenes immediately come to mind. However, above all, the dream sequences that Batman was having were completely unnecessary, and I feel that there could have been a better way to convey Batman's overwhelming bitterness towards Superman without it being as flashy.
"Bitterness," by the way, must have been the only word that stuck out in Ben Affleck's mind when he was getting in character. You'd think two of the most powerful people on Earth would have figured out a way to, I don't know, talk things out before one of them becoming borderline obsessed with the other and wanting to kill them. Guess it's a little too early for the Justice League? (Supposedly coming out in 2018)
Minor complaint: Batsuit is really bulky looking. What's up with that?