liked the movie up to the point where Zod's neck was snapped. I did feel a little sick seeing that. As the movie had pointed out several times, Superman is a symbol of hope and an ideal; he's smart enough and clever enough to find another way
In Superman II he takes away their powers making them human and then throws Zod down a hole to his death, thats way worse than Mos as Zod was no longer a threat. He had NO choice unless he wanted to see an entire family burn and potentially more humans could of followed.
This whole Heroes don't kill NO MATTER WHAT is a pathetic childish fantasy.