Trying to collect my thoughts a bit more...but it's hard to do so because collecting one's thoughts into something coherent after seeing an incoherent mess of awful is really, really tough. Minor spoilers throughout but I'll try to keep the biggest ones tagged.
First, let's start with Superman. He's just nothing. Just a big buff dude who doesn't really do or say anything at all and so it's confusing when people seem to care about him at all. I DON'T agree that he's a murdery d-bag as so many reviews have led me to believe. I think he's shown as someone legitimately TRYING to do good here. He's probably the most heroic person in the entire movie. He does SOME stupid things, but on the stupidometer of this movie, his stupid things fall pretty low on that scale.
Then, there's Batman. Reviews and buzz and trailers had me thinking if nothing else, this movie would NAIL Batman and possibly become the gold-standard for Bat depiction in the future. HA! HA HA HA! If you thought Burton's Batman was a stone-cold killer, you haven't seen ANYTHING yet...if you thought Nolan's Batman was kind of a dick, you haven't even BEGUN to understand the depths to which Snyder is willing to let his Bat sink. Hand-to-God, I think Batman is the VILLAIN of this movie.He's willfully ignorant of facts, he SHOOTS people...in the FACE, and blows them up, stabs them, maims them, burns them, etc...and he wants to KILL, Superman (not merely, "Be prepared to fight, and kill if necessary") because...they never EVER come close to explaining why. Batman thinks Superman has the ability and strength to destroy the world, so he's like "I'm gonna KILL him Alfred, and that will be my legacy." WHAT THE F*** DOES THAT EVEN MEAN?!?!?!
For the world's greatest detective, this guy ignores facts, and can't figure out what Lois Lane and an only half-engaged Superman do, because he's SO singularly focused on MURDER that when he adds up two and two, he doesn't get four, he gets "MURDER". Add to it yet another movie that's wholly uninterested in Bruce Wayne, and gives Affleck very little to do with the role, and Batman/Bruce Wayne flip flops between just kind of a lifeless grimdark jerk and a bloodthirsty serial killing villain.
Eisenberg is ATROCIOUS as Luthor. There are TONS of bits of dialogue, from almost every character, in this movie that feel like complete non-sequiturs. Batman's "Do you bleed? You will" line comes kind of out of nowhere, for example...but NOBODY has more of these atrocious, non-contextual bits of dialogue than Lex. "The red capes are coming," thing...I STILL don't know what the hell that is, and I've SEEN the movie. I have NO idea why he's excited to see Bruce Wayne and Clark Kent together...AT ALL. He also puts a jar of pee labeled "Granny's Peach Tea" on Holly Hunter's desk at one point, to intimidate her. So, there's that.
Wonder Woman...well, I guess reviews are technically right in that she's sort of the lone bright spot, but only because she shows flashes of personality, not because she's a particularly well-developed character or anything. She shows up. She's mysterious. Then she is getting ready to just peace-out...AFTER she's seen all this crazy stuff happening...and it's only when she sees it on the NEWS that she's like "Oh, I better do something about it." It's so DUMB, I can't believe it.
Doomsday...sheesh. If you thought Venom was bad in Spider-Man 3, or Phoenix was bad in X3...well, you've got a new low-bar to measure character depictions by. He's got a nebulous, ill-defined set of powers, his origin is lit on fire, then peed on to put out the fire, then lit on fire again, then dragged through manure, and the rumors about him becoming more spiky than what we see in the trailer are FALSE. This shot, from the trailer:

is as spiky as he ever gets. In fact, when he's "born" he looks EXACTLY like an orc being pulled from the mud in LOTR.
And I hate that I just spent SO much time on the characters, because it's WAY more time than Snyder spends developing them. The whole movie basically just feels like Snyder and Goyer sat down and said, "Okay. Batman v Superman. They fight each other, obviously...so how do we GET there? Let's work from there backwards." Unfortunately, that leads to them ignoring that Batman is supposed to be a brilliant detective, Superman has super powers like super-hearing and X-ray vision, Lex Luthor is clearly and obviously guilty and evil, and they just leave out all kinds of things that could have been done and talked about and shown and they throw LOGIC to the side just to get their fight...their fight that ultimately doesn't even matter because, as we all know, Doomsday shows up and they start fighting together.
Then there's stuff like the effects...it's SO busy. Lots of swirly twirly CGI, and crackly electricity and bright flashes of light and it was just off-putting. Seeing a CGI Batmobile trundle around not that far removed from Nolan doing it all with a real car (or a miniature) is not enjoyable.
or the way people in this movie are SO INSANELY STUPID...here's a taste from the OPENING SCENE, so I won't even count it as a real spoiler:
The opening scene shows the events of the Zod/Superman fight from Bruce Wayne's POV. He's driving through Metropolis to try to get to the Wayne Financial building. Everyone in the building is just sitting there, watching the terraforming machine LEVEL Metropolis and crush people and cars...UNTIL Bruce Wayne calls some guy named Jeff and tells him to evacuate the building and he's like, "Okay people, the boss-man says we should leave" REALLY??? Your employees literally can't think for themselves enough to be able to SEE a giant destructive force and go "Hmmm...maybe I should move AWAY from that thing." ? And this is probably not even the DUMBEST thing in the movie. There's also a moment where there's all kinds of crazy crap happening RIGHT OUTSIDE THE WINDOW of the Daily Planet...and so of course everyone is watching it on TVs in the conference room. Not kidding.
or the way like at least a solid quarter of the film's run-time is dedicated to this stuff with Holly Hunter and the Superman Inquisition and stuff, but with EVERYTHING else that's going on around it, none of it matters AT ALL...like, not only does it not matter at the end of the day, it doesn't even matter IN THE MOMENT. They'll show some thing happening, and then Holly Hunter will address it in a Senate panel or something and it's like "Wait, we've ALREADY seen that what you're saying right now doesn't matter AT ALL."
or how I just don't really need suicide bombing in a superhero movie...there's that too.
I wish I could write a more coherent, less rambly take on this movie's plot, and its failure to mesh a "political thriller" with a superhero movie, but it's such an incoherent mess of a film, it's impossible to collect my thoughts properly. Stuff just happens here, and it feels like it's happening all out of order. By the time it's time for Superman to actually appear in front of the Senate, we feel like that bit of the story is over already and we've moved on, but here we are still devoting screen time to it. The best analogy I can come up with at the moment, would be if, in The Dark Knight Rises, Batman KNEW that Bane was basically the number two guy or one half of whole instead of the undisputed leader, and still spent all this time devoted to treating him like THE GUY and Bane still made all his speeches about being THE GUY...if everyone, even the characters in the movie, already know the outcome of a plot point, that plot point is done, stop showing it to me.
I am still a fan of Man of Steel, and as such, I was looking forward to this, even with the negative reviews, since almost all of them focused on how "bad" Superman was and that it's just an extension of Man of Steel, I figured "Well, if the only thing they really get WRONG (to me and my tastes) is the appearance and origin of Doomsday, I can swallow that pill if it all works with the rest of the story." I kinda wish I'd walked out somewhere around the suicide bombing and just politely asked for my money back or a voucher to see another movie or maybe even a free small soda or something, because I think this is the worst movie I've seen in a theater since Transformers Revenge of the Fallen.