I liked that Snyder basically took "yellow sunlight" and spun it in terms that make a little more sense and were a little more topical. It also flowed well with Krypton's background in the film and the climate change warning that was the moral of that part of the story.
Basically, compared to Krypton earth's too healthy a planet and Clark couldn't cope with it. It's the kind of twist I really appreciate in adaptations.
That's always a sticking point for me. How do you get Zod at a place where he can really be a credible threat to Clark, when Zod hasn't spent nearly as much time under the same conditions? How is Supergirl supposed to keep up with Clark? It raises questions that don't have an immediate, satisfying answer, and it only gets worse the more powerful Clark is. And since I like a stupid strong Superman......The other kryptonIans wouldn't be able to match up to clark in that area.
That's not a bad idea at all, actually.