I'm a little confused by it's poor reception. While a lot of the complaints are valid (the story was a bit of a mess, and it did seem a little convoluted at times), others seem entirely nonsensical. For example, some reviewers claimed that the movie was utterly humorless, which is a straight up lie (Alfred in particular provided a lot of comedy). And, why does it need to be filled with humour anyway? Tons of movies aren't focused around comedy, for example, dramas and some serious action movies. These movies aren't bad for having little to no comedy, so why is Batman V Superman bad for not having as much as a Marvel movie?
And there were some really great performances too. Jeremy Irons (Alfred), Batman/Bruce Wayne (Ben Affleck) and for the short amount of time she was in it for, Wonder Woman (Gal Gadot) were all great performances. And Henry Cavill as Superman was much better than in Man Of Steel.
And the absolute most confusing complaint was that the action scenes were bad. They weren't. At all. They were incredibly brutal and exciting, with each blow feeling meaty. Superman and Batman's fight was super intense, with both gaining the upperhand multiple times. Along with this, Batman's fight against Lex's goons was amazing to watch. He was agile, quick and brutal. Much more intense (and accurate to the comics) than the Nolan films Batman. However, Batman does kill people in this movie. Which I'm not a fan of, but it doesn't ruin the film.
Sure, the final fight was basically all CGI, but what were people expecting? How could Superman and Wonder Woman fly and jump around at high speeds, beating up a giant monster like Doomsday, if everything was done in practical effects? Sure, Mad Max: Fury Road has amazing practical effects (and is an amazing movie in general), but the type of action in those movies is very different from fight scenes between gods, like Superman and Doomsday.
SUPER SPOILER WARNING
Overall, it wasn't the best movie ever. Hell, it wasn't even the best super hero movie ever, and it does have some serious flaws. But it is nowhere near as bad as most reviews are saying