There are plenty of reviews that will tell you Batman v. Superman: Dawn of Justice was poorly paced, overstuffed, and hyper-serious. As well as that its themes and messages are near-fascist. All of that is true, but there is a core problem beyond all that: this movie features neither Batman nor Superman.
As mythological characters (and believe me, the filmmakers know they are myths, hence Luthor's constant on-the-nose speeches) these heroes have an essence, a set of defining characteristics that make them that character as opposed to another. As Mike Rugnetta of "PBS Idea Channel" put it "If Harry Potter didn't cast spells, if he didn't have a lightning bolt scar, if he sold shoes at the Mall of America, drove a Prius and had a Swedish accent, would he still be Harry Potter?"
The characters of Batman and Superman have been around for over 75 years. While very early issues had some bugs to work out, the characters quickly grew into themselves.
Kal-El was the last child of the dead world known as Krypton. He was raised on earth by the Kents and instilled with a strong sense of responsibility, honesty, and, yes, justice. Clark Kent takes on the identity of Superman to help people in need. He is a paragon of virtue who has the powers of a god. Despite struggling with the conscience of a man, Superman always takes the higher path. More even than his powers, this is what defines Superman
As for Batman, in many ways, Bruce Wayne died in that alleyway with his parents. The man who grew up to become Batman uses the mask of Bruce Wayne to help him in his caped crusade to make sure no one else suffers like he did. He has no powers, but he uses his martial arts skills, gadgets, and most importantly, his keen detective mind to fight crime. Above all, since and because of the event of his parent death, Batman would never kill, and never, ever use a gun.
In Batman v. Superman, the characters who call themselves Batman and Superman do veer sharply from these basic principles. "Superman" cares nothing for civilian casualties and is willing to kill on several occasions.
Granted, he has pulled back from these since Man of Steel, but he's still far from actually being Superman. His parents are equally out of character: "Ma Kent" tells Clark that he doesn't owe the world anything. In the comics, she instills the sense of altruism that leads him to take up the mantle of Superman. "Batman" uses guns, brands criminals with a hot bat shaped iron, and generally seems not to care about Gotham's apparent human trafficking problem.
Ben Affleck says that his Batman is "farther down the path" than other versions "filled with rage" and "war-torn." This is fundamentally wrong. This "Batman" is putatively mature and should be beyond rage. Rage is what an impudent, young Bruce Wayne would have felt before becoming Batman. Batman has moved past rage, he knows it would only get in the way of his crime-fighting and cloud his logic.
Don't even get me started on Lex Luthor. The film's "Batman" is closer to being the villainous, alien-distrusting Lex Luthor than Jesse Eisenberg's turn as a mythology-obsessed Martin Shkreli.
What astounds me is that within the confines of the plot, this would have been a far better movie had the characters acted consistently with their true selves. For example, instead of trying to beat the help out of Batman, Superman could fly just high enough to be out of his reach and say, "Listen, Bruce. Obviously you have a way to stop me or you wouldn't be here. But Luthor has an innocent woman and is going to kill her unless I bring him your body in the next hour. So go ahead, take me out. Just save her, save Martha Kent."
After all, the real Superman would gladly die to save an innocent life, and he would trust in humanity's good nature enough to believe Bruce wouldn't go through with it anyway.
Or how about instead of shooting and blowing up the Russians carting the Kryptonite to Lex, Batman could jam their guns (we know he can he uses the jammer later) knock some of them out and intimidate those still conscious into selling him the Kryptonite, for which Batman pays with marked bills and alerts to police.
Very little effort could have made this movie truer to the characters and far less contrived. However, to make the characters into the killers we see on the screen was a deliberate choice. Those responsible have all said they wanted to make a "more real" superhero movie. From this film, it is clear that in their eyes "real" means grey and hopeless.
If the characters are historically so well defined, how could the filmmakers fail so miserably? To start, they seem ashamed that the movie is based on comics. David Goyer, who co-wrote the screenplay has made his views on comics quite clear. so to avoid that "comic-bookiness" they went with the least fun, darkest source material they could find: Frank Miller's Dark Knight Returns.
Frank Miller is, in my opinion, the worst thing to happen to comics. He is racist, penning a comic about how all Muslims are terrorists; He's sexist, penning paragraphs in his scripts describing a female character's rear and writing feminists as people who believe men are nothing more than sperm banks; and he is fascist, many literary analyses of his work have deduced that he believes that might makes right, and everyone should bow down to the man with the biggest gun.
And, this is the man who got the top spot under "Special Thanks" in the credits.
It doesn't help that Snyder, despite being a great director of photography, has also proven himself to be incredibly bigoted and backwards minded (see his self-proclaimed 'feminist' film Sucker Punch).
It is a travesty that these beloved characters are left in the hands of people who have such derision for not only the source material but also for the ideals to which the material aspires. In a world rife with hate, xenophobia and violence, we need these modern myths to rise above and inspire us. They should be a light to guide us, not a dark mirror for out worst traits.