Speaker for the Dead had a great start, but the ending proved to be a giant disappointment. First off, I was against the entire idea of continuing the story of Ender. I really thought it should have been left up to the reader's imagination. Ender's Game should have been a stand alone without any sequals. Speaker for the Dead is a whole new mother. Ender's character was changed beyond any recognition. Beyond any at all. And while it has been 3000 years and last we saw him, he was an adolescent boy, I felt I was looking at an absolutely different person. The entire relationship with his sister had also vanished and it was hard to imagine that he and Valentine were even siblings. In my opinion, much of the characters were ruined. Novinha, who was wonderfuly developed at the beggining of the novel was unbelieavebly weak for about 2/3 of the book (not as a person, but as a character). Her complex personality, as seen at the start, dimmed down to a flat character with a considerbly limited amount of emotions (either scorn or histeria). Some plots were also ended abruptly in the most uncomfortable manner.
Spoiler
The entire affair with Miro and his sister fell down dead like a rock. There was no resolution, no diologue, no nothing. It's almost as bad as Greek trajedies, where plot found the resolution to the characters' shameful deeds through suicide. In addition, found that Miro's cripplement played no significant role in the story.
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That's what happens when people grow up. 
