There was a lot of things to like about the movie, but it's dragged down significantly by an awfully written Lex Luthor, who is little more than a total nut job, and as such wastes the man vs "god" story set up in the first 3/4ths of the movie. Instead, that entire plotline of turning humanity against Superman is tossed aside for Luthor creating Doomsday, a monster that without Superman's intervention would kill not only him, but destroy the entire planet, with humanity having no hope of preventing it whatsoever. He has no end game by the conclusion of this movie. He isn't some eccentric genius, or even a brilliant madman (character deviations I would have been ok with), he's just a complete looney who would set the world on fire to kill Superman. Nevermind that this goes against the very core of the character that is supposed to be Lex Luthor, but again, it just completely undermines the conflict they build up throughout the rest of the movie.