Card deals with ethical issues constantly in this series, not as an after-thought or a side-thread, but as the main theme. The science is not the focus, and at times it's not even very credible, but that doesn't affect the soul of the story. There is a lot of spiritual under-current in this story as well (a bit too much for my taste).
This might quite possibly become the reference manual for humankind when we eventually run into extra-terrestrials, just like Clarke's works were for the Apollo mission.
