Some people say that there's no plot and the story is too simple but I can't disagree more. The show makes you ponder about the deeper question behind it. Why are they attacking? Why should I fight? What happens if I don't? Am I alone? To me, the story is absolutely stunning (and I ended up crying a little while watching). It is some what light hearted but those who have watched anime like Bokurano will definitely be struck by the similarity between the underlying theme. The main issue with this is the animation. However, I came to watch it with the full knowledge thatit is a mixture of anime and comics animation so while it is a major drawback, I was not too much of an issue to me.