Ender's Game was okay, except for the ending (i.e, what you alluded to when you talk about how stupid it was that the Buggers didn't realize people were sentient). Card was able to write the same book again by writing Ender's Shadow. The rest of the books were just stupid. Speaker for the Dead was awful, Shadow of the Hegemon or whatever was ridiculous - the notion that children would be running armies was totally idiotic, when in fact the only reason that they were used in the first place in Ender's Game was because they could be fooled.

And that is only if you look at Ender's Game as cheap entertainment. He has some of the most abysmal writing in the world when it comes to characterization and description.