“Without question, Speaker for the Dead and Xenocide collectively tell a far more interesting story than the first book of the Ender series. It is difficult to find another book or series where characters grow and evolve more convincingly and interestingly than the manner in which Ender Wiggin matures in these books from a genius child into a genius adult.
It helps to think of these books not as direct sequels to Ender's Game, but as grown-up versions of the Ender character and story. The universe, subject matter, setting, and characters have all evolved and grown into something far more interesting, intriguing, and compelling than the original action sci-fi tale of the first novel.
The philosophy and morality of life, the definition of existence, and the dilemmas of peaceful coexistence among a future world filled with more than just humans are the key topics of these books, and they are explored with well-crafted story-telling and deep, inspiring, multifaceted characters that truly leap from the page.
Card's treatment of computer sentience alone is a far more interesting and involving tale than books whose sole purpose has been devoted to that topic, and is rivaled only by the depth of character and circumstance given to the robots of Asimov's universe. And yet this is only a supporting character in an even more elaborate story exploring the nature of life and sentience.
The characters in this story will frustrate you, entertain you, and, most of all, surprise you, as they grow, mature, and evolve right in front your eyes.”