Supes and Bats disagree with each other, and Lex capitalizes on this to do crazy stuff. That's the premise of the movie and one pretty much everyone expected from the trailer or even just the title. These are somewhat different versions of the characters we're used to though. Instead of being brilliant, all three are simply more
Judging from this poster, they are both ashamed of being in this film.
Oh and Batman uses guns, doesn't really care if people survive encountering him (giving even more contrast to Superman), and trips balls often. OFTEN. It's awesome! Also worth pointing out that Ben Affleck does a great Batman, but an even better Bruce Wayne. I wasn't checking the clock but I believe there's more Bruce than Bat in the film which is actually pretty cool.
Despite having all these big superhero names most of the action is still reserved for the last act, which makes it all the better when you get to it. The film is clearly DC's platform for building the Justice League too, giving little glimpses of other characters in their universe.
Overall I can agree it's not the best DC movie ever (hard to compete with my fave "the Dark Knight"), but I still very much enjoyed it and would definitely watch it again. I give it three and a half beat downs out of five.