First off, the prologue was completely unnecessary (I'm talking about his parents being gunned down, not his reaction to Superman's destruction from Man of Steel). Just as we've seen Spiderman's origin story time and time again, we've also seen Batman's. At this point, everyone knows his origin story. And the slow-mo wankery actually made it worse. It felt like the scene was shot because they wanted to show off some slow-mo effects instead of using the slow-mo effects to accentuate the scene (as it should've been).
Ben Affleck as Bruce Wayne/Batman, and since actors have to play him in such a way that's essentially two different characters, I'll address each of them independently. As Batman, he was absolutely fantastic; easily the best on-screen Batman we've ever gotten. He's actually a detective, and he actually uses the Batcomputer. It's that facet of Batman that we've never seen in film before. The only thing that I'm concerned is that while he does kill people in the movie, I don't actually have a problem that in particular. I know people are outraged because of it, which is silly, because Keaton's Batman is beloved, and he definitely kills a few times (and IIRC, Bale did, too); it's not as pronounced as here, but it still happens. What bothers me, is that the explanation I most often hear for the Joker's grills is because of run ins with Batman, but if that's the case, why wouldn't he just kill him? If someone can answer that, that would be awesome. As far as I know, that's just speculation, right now, so there may be another reason entirely.
His Bruce Wayne, though, wasn't really that great in that the playboy aspect wasn't really all there. They tried it with Diana and him, which was fine, but other than that, there wasn't much going on there. Don't really blame them, though, they filled up their screen-time pretty much to the max.
Jesse Eisenberg as Lex Luthor... wasn't terrible, but he wasn't very good either. Really, he was barely even Lex. He was miscast. There is one exception to this, though: The scene on the helipad and his interactions there with Lois and Superman. It showed he was actually a threat, and how manipulative and cunning Lex can be. Take that scene, tone down the... Jesse Eisenberg-ness of it, make him bald, and up his intimidating factor a bit and you've got a pretty damn good Lex. Do those things, and not only would he have been in control, it would've felt like he was in control.
Even though Gal Gadot as Wonder Woman didn't have very much screen time, when she finally did show up in her costume (which itself is pretty rad), she was great. Single best moment is that leap at Doomsday. And speaking of Doomsday... there was no reason for him to even be there. Although, I did like that they had the balls to kill Superman (and of course, I know it's not permanent, but I wish they hadn't made that so obvious).
The first half of the movie tried (and I consider it to have failed) it it's dynamic in trying to explore the implications of security and even religion in the instance of a god-like alien among humans. The idea has a ton of potential for depth, but the movie didn't really touch on it enough, and definitely not to the extent they should have. What I would have done is cut out Batman's origin story (since everyone knows it by now) and as much fluff as possible in order to extend the court scene. It was way too short, by itself, it was only there because of Lex framing Supes. You could have kept that, but extended the scene and it probably would have been more impactful, especially if it wasn't so overtly hinted at what was going to happen. In general, the scene was just strange, with it being completely silent before the explosion happens. It almost reaches jumpscare levels of absurdity.
The second half is what lives up the the title of the movie. Batman and Superman engage in fisticuffs, and unsurprisingly the action is fantastic. I do like that Superman completely wipes the floor with Batman even after getting hit with a kryptonite bullet. Don't like that Batman basically won. Even though it's not really brilliant writing, I do like the reason they stop fighting: because both their mother's names are Martha. It's a bit silly now that I think of it, but I like it because I don't think I've ever realized that, until now.
Another scene that's silly for fans to get annoyed over is that one where Aqua Man, the Flash, and Cyborg get cameos. The reason I don't think this is all that bad is because they do it all at once, and it's almost over as quickly as it started. They show each of the cameo clips back to back and it moves on. It's setup bait for more movies, but I don't really blame them for doing that. They're already behind Marvel.
tl;dr: Everyone knows Batman's origin story. Ben Affleck and Gal Gadot were both great, Jesse Eisenberg was meh. Doomsday was shoehorned in. Great action and visuals.
Well, I think that's it, really. I'd be curious to see other people thoughts on the movie.
