Zack Snyder has outdone himself with this movie. I hope it's appreciated as much as it should be.
1. This is really only a superhero movie on the surface. Director Zack Snyder, known for contemplating the dark side of heroism in movies like Watchmen and Man of Steel, has made a (mostly) brilliant movie about who we idolize, and what the costs are.
2. The movie actually starts back in Man of Steel, when the world engine is crunching the planet, but the events are shown from Bruce Wayne's perspective. If you haven't seen Man of Steel, you will be completely lost.
3. I was very worried about Ben Affleck playing Bruce Wayne/Batman. Every time I think of Ben Affleck connected to the word "superhero", I think about Daredevil. I don't want to think about Daredevil. But thankfully, Affleck pulls it off. The Batman scenes in the film have elements of suspense, torture, and real horror. This is not a nice Batman.
4. The action scenes are epic, but there's not a lot of them (despite what the trailer may lead you to believe). Snyder doesn't let the action get in the way of the story, and he takes time to build plausible reasons that Superman and Batman would become enemies, with Lex Luthor in the middle. It's full of religious imagery and commentary, both Christian and pagan.
5. As in Watchmen, the characters are metaphors for deeper themes. Lex Luthor (played by Jesse Eisenberg in a pretty creative role) is obsessed with god issues; one of his lines is, "God is tribal. He takes sides." Batman and Superman each represent a different take on the meaning of the world. Superman represents a life with purpose, where your goal is to find your place in the world. Batman represents life as pointless and random; the only meaning life has is what you force from it.
6. Most importantly - and this is what sets the DC Extended Universe apart from the Marvel Cinematic Universe - the movie shows that actions have consequences. Large-scale destruction will kill a lot of people. Some of those people will carry grudges. The mountain scene where Clark talks about saving his flooding farm brings up existential issues that were pointed out by philosophers like Albert Camus - we're all murderers sometimes.
7. The camera work is excellent, and there are some truly epic scenes scattered throughout the movie.
8. Gal Gadot plays Wonder Woman. She was the right actress for the role, but Wonder Woman did not fit in this movie. She was obviously planted in order to open the door for the Justice League movies, but her scenes were awkward and pointless.
9. Is the movie perfect? No. There are some questionable plot and editing choices. But the fact that Snyder is trying to elevate superheroes to being subjects of deeper social discourse, instead of just making a commercial for the next film, gets him mega points in my book.
If you like your heroes to be silly, stupid Saturday morning cartoons, you might want to stick with The Avengers or Fantastic Four. You may find this movie to disappointingly boring and unnecessarily dark.
But if you usually avoid superhero movies, you might want to check this one out. If you like heroes to exist in a real world with real consequences, if you need a thoughtful and intelligent script that will stick with you after the movie ends, then you may find that this is not only a great superhero movie, it's a great movie, period.