It's pretty near perfect

Rating: 10/10 (24 May 2018)

Spoilers I guess,
I think most of the bad reviews are people upset that Batman kills, Superman doesn't crush him, or some other part of the heroes choices that doesn't line up with the critics personal view of his or her childhood superheroes. I think they are perfect. They are realistic and behaving so, in a fantasy world.
When Batman and Superman have their stand off, there are a few things one needs to understand, and on both sides.
Superman is getting increasingly frustrated with humanity throughout the film. He tries to help, everyone criticisms him, or worse, kidnaps his mom! When he shows up at the bat signal, he doesn't want to fight, he wants Batman's help, but he is at a tipping point, both because of his frustration, and of course because of the precious time he has left to save his mother. When I first saw this movie I thought he jumped too quickly to fighting Batman, but now I see that he's had enough, and it's reasonable to see why if you just watch the film. And even when he starts fighting back, he doesn't want to kill Batman, you can see the inner struggle as he gets closer and closer to, but never really wanting to do it.
Batman wants to kill Superman because his perception of him is so skewed with lies and deceit that Luther purposely sewed into him. He is also blinded by the vision of the future he had, in which Superman has clearly taken over the world and lost all his humanity. He doesn't see Superman as a human until the 'save Martha' scene hits him hard with the realization that even as he is about to die, Superman still just wants to save someone else. And that brings everything back into perspective. Not just 'our moms have the same name!'
There are amazing and gutsy references outside of the films plot, which are meant to be in the future or in the past, especially the future vision, that I think are all perfectly delivered and mysterious enough for us to want more, but not needing it right this moment, and relevant to how Batman makes his choice to kill Superman.
All of the acting is spot on, especially after watching them all reprise their roles in Justice League, which clearly chickened out and tried to be more fun and straight forward like Marvel. Same characters, much worse. No layers, everything had to be said out loud.
My hope is that Batman vs Superman would be DCs benchmark going forward, and that they don't care what anyone says, as long as they stick to the same amazing vision that was present during the making of this great film.