To start, the movie was amazing in my opinion. Do not take the critical opinions or takes on this movie at their word and let them dissuade you from seeing it. With the proper understanding of recent, as well as past storylines in the comic realm, and of course a general love of the characters shown on screen, Batman v. Superman: Dawn of Justice should be one of the best films you see this year.
For me, it is one of the best films I have seen period, and would rate it a 9.4/10.
With that said, I believe the movie can only be enjoyed to the greatest measure if the viewer is aware totally of what director Zach Synder is doing in the film and why. To understand that there are a few things to watch/read ahead of time that will all together turn BVS into a true experience rather than just another trip to the theater.
Oh and there could be a ton of spoilers in here, just in case you are the type of person that hates those/wants zero background understanding of what you are watching on screen and would rather be confused while watching the movie. Your call there.
Prerequisites:
First off it should go without saying any viewer should have at least a semblance of knowledge of the DC characters and their backgrounds; if you don’t have that, where have you been for the last 80 or so years?!?
#2 Watch Man of Steel. This movie is really a direct sequel to Man of Steel with the rest of the DC universe actually existing now. Like any movie series, you should watch the first installment before seeing the sequels. Pretty common movie viewing knowledge here, and it is also a very good movie prior to the fight scene at the end(except the fight scene is pivotal to the character points of view in BVS, go figure).
Here is where you actually need to enjoy comics/comic based works.
#3 Watch, or read if at all possible the Flashpoint Paradox animated movie or storyline. There is truly only one thing you NEED to understand from this, and it concerns only an ability the flash has, but if you watch/read the story it will better your understanding of the DC characters so broadly it is crazy. It is a much, much deeper story than it would first appear, and is truly one of the most humanizing stories I have ever come across in the comic book form.
#4 Watch/read Justice League: War. The film is again animated here, and it is the opening storyline that DC used to reboot their entire comic universe in 2011(so it is a pretty big deal). This story is not absolutely necessary to understand for BVS, but it completely explains the creatures in Batman’s dream sequence(the Knightmare scene) and where the actual Justice League movies that follow BVS are going to go. If you understand this story, you know instantly what Synder and crew are setting up.
#5 Watch The Dark Knight Returns part one and two.
It is down the list simply because I haven’t organized these by importance, but this is the sheer biggest thing any viewer must see before watching Batman v. Superman. Literally, I can not stress that point enough. This story explains the conflict between the two biggest characters in the history of comics and many of the shots in the BVS movie are taken directly from the pages of the comic. Disclaimer for anyone wanting to read the source material versus watching the animated version of it: this is the one story I have seen a movie version of that doesn’t really lose any of its merit by being transferred to another medium, and if you are not a seasoned comic reader, you are going to be straight up lost going through Frank Miller’s original graphic novel. Absolutely worth it as a read, but be forewarned.
#6 Read Batman: A Death in the Family. The same benefit this story brings is mentioned in a different way in The Dark Knight returns, but is actually explained here. This story explains why Ben Affleck’s grizzled and older Batman is the way he is, as well as explaining the Robin suit hung up in the Batcave.
#7 Read The Death of Superman. Just do it. And ignore everything after the battle with DD.
#8 Read the first few issues of Injustice: Gods Among US Year One. This whole story would explain another possible issue between Batman and Superman, and is extremely good, but the main thing to grasp is Superman’s use of human soldiers as a possibility.
#9 Know what Kryptonite is. Don’t be lazy.
#10 Know that Jesse Eisenberg is not playing THE Lex Luthor, he is playing his son, Alexander Luthor. This way you don’t get all bogged down on his different take on the performance. (Which by the way makes absolutely perfect sense if an understanding of comics is simply paired with an understanding of how humans work, there are FAR too many negative reviews of Eisenberg’s performance.)
#11 Know that the Omega symbol refers explicitly to Darkseid in DC comics. The use of this in the film is again a reference to Justice League: War.
#12 If you are going to watch the bonus Communion scene: Know who Steppenwolf(comics not the band) and Yuga Kahn are. I still haven’t decided who I really think Luthor is in the room with yet. Also know what a Mother Box is, because the creature isn’t just holding three random black boxes.
And finally!