What sets Ender in Exile apart from the the rest of the series is this: it is less than the sum of its parts.
A handful of its chapters had already appeared in short story form on Card's online sci-fi zine, Intergalactic Medicine Show. These stories were interesting and self-contained in their own right. But within the context of a novel, they strike me as being Card's Tom Bombadil: incidentally enriching to the established universe, but irrelevant to the narrative at hand.
The narrative at hand is Ender's post-war recovery, discovering the egg and writing the Hive Queen (the book), the changing relationship between Ender and the rest of his family, and (perhaps most of all, thanks to the dangling cliffhanger) dealing with the last of Bean's scattered children. If you've read the previous books, I don't think it will be any terrible spoiler to call this child by the name he calls himself, Achilles.
Each of these compelling plot threads are given at least an adequate, and sometimes a very compelling resolution—but only when I force myself to consider them as further self-contained short stories. Within the context of the novel, each is breezed through with such haste that I was on the second to last page of the book before I realized, "Oh, that was the dramatic climax, wasn't it."
Ender in Exile is published as a novel, but it's really a collection of episodic short stories that constitute a novel only in appearance. By sandwiching them together with hasty transitions, they are all diminished, competing for attention, never really integrating. Each part, if it had stood alone, would have done better. Summed together, they are all lessened.
In my ideal world, Card would have released a collection of short stories, perhaps a novella, dealing with things like the Alessandra/Dorianna/Morgan plotline and the gold bugs. Or—perhaps better still—leave them as-is on Intergalactic Medicine Show, affirming that Card's contribution to the zine actually has some worth and isn't just a venue for double-publishing the same work.
In my ideal, Ender's recovery, dealing with the last Hive Queen, dealing with his family, and dealing with Achilles would have spanned an entire novel at least as long as Exile instead of a few scattered chapters. The situation on Virlomi's colony world and the development of Achilles deserved far, far more than the two or three chapters they got. In those two or three chapters, Card telegraphed an emotional punch of a plotline. But I knew I would have cared far more about if I had really known young Achilles, if Ender's post-war troubles had been consistently expessed as an ongoing plot thread that demanded resolution. The emotional punch Card telegraphed was barely a tap on the shoulder. It still made me wince, but only because I was led to expect more.
Card said this is his best Ender book yet. I couldn't disagree more. Yet, it's not a bad book. It's still Ender, and it's still Card, which means it's still compelling enough fiction for me to keep reading all the way through to the last page within only a few days of purchasing it. That's more than I can say for the vast majority of books I buy.
The highlight of the book for me was Ender's touching reunion with Valentine. So well done. Though I wouldn't know until later that that early chapter would be the emotional climax of the book for me, it is not diminished. I only wish I could say Ender's collision with young Achilles delivered even a fraction of the catharsis it deserved.