I feel like he did change significantly between both films and I don't understand why he is still getting so much hate. He's visibly anguished over the fact that he missed Wally's bomb at the senate hearing, he goes to great lengths to help whoever he can, almost at the cost of his job and his relationship, dropping things at a moment's notice to save a girl in a burning building in a totally different country.
The one that immediately comes to mind for me is Luthor. Even after everything he's done, between Africa and the hearing and Martha and Lois; he still saves him when Doomsday goes after him. This guy killed hundreds of people, almost murdered his mother and the woman he loves, and unleashes a monster that killed thousands more, yet, when that same beast was about to murder its creator, he saved the biggest monster of them all.
I'm sure I'll get the usual cynical responses about Superman "only killing civilians" or something, but I truly believe that, by the time we reached his death, it felt earned, which is something I didn't expect to be able to say.