Pros: well-written; interesting ideas; characters who were well-drawn and developed over the course of the books(s). I'll definitely be grabbing more Butler from my wife's shelf.

Cons: the conclusion(s) were extremely pat and unchallenging (particularly the third book), and ultimately the most interesting question raised by Butler (below, for spoiler-ish reasons) is very underdeveloped.

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In the book, the alien species that saves what is left of human-kind identifies that human genetics has an inbuilt, ultimately destructive conflict between intelligence and a drive towards hierarchy - the latter being something that the aliens supposedly lack. But the way this is developed was frustrating and unsatisfying to me. On the one hand, the aliens do some pretty hierarchical things - on the small scale, impregnating a human character involuntarily; on the large scale, involuntarily sterilizing the entire remaining human race (later rescinded to "only" deporting them to Mars). And on the other hand, the supposed flaw in humans - despite being an incredibly important part of the plot - is explored only shallowly, with repeated, blunt points that "hey, humans kill each other"and "humans give too much deference to tall men". Given how important this was to the book, and how potentially interesting it could have been I would really have liked to have seen it developed more - how is it that humans are so stuck on this? What is it that can't be trained out of them? And vice-versa, how do the aliens make decision other than hand-wavy "we've got a mind-meld and consensus"? This doesn't make the book unreadable, or anything, just... a lost opportunity.