The next two books after Ender's Shadow are equally enjoyable. You get a good look into the personalities of Peter Wiggin, and especially Petra. It struck me that Peter Wiggin isn't quite the sadistic monster he was in Ender's Game, not even what I'd call a sociopath - apparently he grows up & out of his childhood issues. You also get a delightful glimpse at Ender's parents. turns out the brains didn't come from a cereal box after all. ;)

Card is one of my favorite authors. But there are some series by him I couldn't get into - Seventh Son was one of those.