So let me start by stating two facts. One, I've heard mixed reviews, so I'm aware that there could be flaws in everything I state. I don't watch many movies and I don't really know what goes into their production. Two, I'm not really a DC fan. I'm far more acute with my knowledge of the Marvel universe, but as far as DC goes, I don't really know much at all beyond the huge five guys in the Justice League.
That being said let's move on. In my opinion, this movie is the best superhero movie DC has ever made. Unfortunately, that isn't saying much. I also wouldn't say the movie deserves much. There is a whole lot they got wrong, and I think the mistake they are trying to make is that DC is specifically trying to make the movies distinctive from the comics (a horrible misstep since the multiverse is already so convoluted). If a movie begins by saying "Based on the DC Comics" you know that it won't hold true to the canon.
One of my biggest issues was the plot holes. First, Superman is blamed for causing the death of people that were killed by bullets. Why would Superman ever kill people with guns (except to maybe hide the fact that he killed them I guess? That's a real stretch). Second, Superman seems to have a spidey-sense when Lois Lane is in danger. Multiple times he shows up to save her without possibly even knowing she is in danger, let alone her exact location to save her in the nick of time. Third, Lex Luthor's dealings with the Kryptonian ship are vague at best. It's impossible to be able to tell how he really accomplishes the things he ends up doing. Also sort of related. We can't really tell what Lex Luthor's goals really are. We get some vague answer, but his reasons for wanting thins seem to change rapidly throughout the film. Lastly, Batman is so not Batman. Batman literally kills more people in the movie than Superman does. That sentence is so wrong in so many ways. My friend told me about an interview they had with Ben Affleck that apparently the Batman he played was a jaded Batman that was done playing nice and just wanted to take revenge or something. But if that's true there was literally zero information int he movie to tell you that. I honestly thought that the movie was saying he became Batman after Man of Steel solely to kill Superman.
Those are my biggest issues with the movie. There are more, but they're not large enough to draw attention to I would say. This movie does do some good things. Wonder Woman was, in general, a pretty decent character. She's not crucial to the plot (and rightfully so), and her importance only grows apparent later in the film, so it was done well. Also, it sets up for the Justice League movies a bit by hinting at other heroes (though I would argue that they show far more than is necessary for the film).
But anyways, the movie overall wasn't atrocious. It's bad, yes. But it's no Green Lantern. I'd give it a four out of ten.
P.S. I Am Legend predicted Batman V Superman.