Tell me, in detail, how they developed the single relationship in this movie that needed to be developed (Bruce Wayne and Clark Kent) in a meaningful, way that earned the loss/sacrifice at the film's end.
That was the most important thing they needed to nail and overwhelming, people have come away feeling like that didn't work at all.
Don't get me started on Lex and his lack of depth beyond...what we got.
...
Okay, ignoring the sudden change in criteria from "any character development" to "this specific piece of character development..."
Bruce Wayne starts out regarding Clark Kent as the latest obstacle to be run over in his crusade. As the most dangeous rogue in his gallery. A threat so unbelievably potent, unbelievably dangerous, that it cannot be allowed to exist. That the whole world can be categorized like that; he's even come to regard himself as nothing more than a criminal, albeit one that hunts others. So he's in kind of a dark place. A place that only gets darker as the movie progresses and he gets pushed further over the edge by Lex's manipulations.
Meanwhile, Clark Kent is wrestling with what it means to be Superman. He's becoming frightened of the effect he can have on the world, wondering if he really has the right to pull these levers. So when he sees what Batman has begun to do (and he's only begun, the branding really does seem to have happened more than once), and it disgusts him. So he begins to tackle the threat of the Bat-Vigilante as Clark Kent, as opposed to Superman.
By the middle of the movie, things are coming to a head for both characters. Clark has left the building entirely, just about, feeling that Superman causes more damage than he heals. And Batman is prepping for outright deliberate murder. But then... Clark comes back. Because he loves Lois, because he's come to realize that his actions having consequences isn't something that would go away if he had no powers. That you can't save everybody, but you can never stop trying.
Then, Lex has his mother. Superman rejected the fight on his own terms, but he's forced into it by Lex. So he decides, he's going to approach Batman, not as a foe, but as a person. One who he believes still has good in him, a far cry from his views earlier in the movie. Batman, meanwhile, is lagging behind in his epiphany. So while Superman is just trying to subdue Batman long enough to convince him to help, Batman is really trying to murder Superman. And he very nearly does. Until Superman says the Martha line. And Batman is suddenly shocked into remembering that the people he fights aren't just criminals, or monsters, they're
people. It's something he clearly hasn't thought about for a very very long time. And the shock of that is enough for him to help Superman rescue his mother.
And then Superman dies. Twice. And this links back to the "men are brave" thing. Because Batman's whole thing with that was that you have to be able to feel fear to be brave. That Superman's inhuman strength and toughness makes him less, makes him incapable of being a hero. And then he's shown to be wrong. Batman at the end of the movie is ready to begin trying to heal, a far cry from the burned out shell of a man at the beginning.
And that's character development.