A suffusion of yellow
I agree with you -- there are a lot of things Superman of the comics wouldn't do. But keep in mind, he wasn't Superman in this movie: He was Kal-El of Krypton. It's the events of this movie that make him Superman. This movie shows why he adopts certain creeds and policies, such as Do Not Kill. It's a true origin story, one we've never seen before in film for him.
just watched the Supergirl vs Red Faced episode and the line where Henshaw says "people aren't scared of your cousin because he has god like powers they're scared of what he might do if he lost his temper." which while corny as eck did make me wonder if it was a deliberate line given that the Movie is about what could Supes do if he lost his temper.
in other words I'm agreeing that taken as an alternative universe What If ... story, Man of Steel works fine