The thing about Ender's Game is that it originally was a short story. To make a book out of it is hard as it is, much less multiple books. I didn't read the shadow series or whatever they are called, but I read the first three of Ender. The first was definitely the best, but it still felt "padded" at times (b/c of the short story roots I guess). The other two were ok, but didn't "wow" me like the original. The third book is also very "out there" with all the metaphysical musings.