I could go on at length about what was wrong with Man of Steel. But it boils down to this... they took a character who, for 70 years, was a bastion of truth, justice, etc; an upstanding paragon and the literal big blue boyscout, and transformed it into a navel-gazing self-centered and self-important whiny brat of a superhuman because, well, that's how he's written in a lot of the current DC new 52. Basically, they listened to all those comic book readers who claim superman is boring, and tried to make hum... unboring to that particular section of the audience. They also tried to make a batman movie using superman; see this for explanations of why.
I do agree, that what they did with Zod was brilliant. Raising him up from being a bog-standard megalomaniac to being someone who was genetically predesigned to be a warmonger incapable of seeing that what he was saying was not right was a great idea in a movie full of otherwise bad and recycled ideas. that and the kryptonian sequence are really the only parts of that movie that work for me. (the two minute scene where clark talks to the priest is effective too, but it is quickly drowned by the surrounding scenes)
I have to say I agree with most of what you're saying, but personally, I'm still conflicted with the
way in which he killed Zod... It felt off, and somewhat forced even, to me anyways.
Sure it made sense in the context of the movie and that particular scene, but years of knowing Superman's "there has to be another way" mentality (particularly well showcased in the movie, Superman vs. the Elite, where he somewhat agonizes over how to deal with them without lowering himself to their level by killing Manchester Black and company), makes me feel that he probably could have, and maybe even should have, tried to find some other way short of killing Zod to incapacitate him.
Granted, I haven't really read any of the comics(except for the
infamous Doomsday arc... Warning, Mild language, and very funny, may not be work safe!), let alone the new 52 stuff(which every thing I hear makes me kind of not want to lately...), so my perspective might not be as well informed as yours...