Spartacus begins with the Enterprise answering a distress call from a ship that turns out to be crewed by androids, who are fleeing the planet of Vemla. The Vemlans themselves consider the androids slaves and rebels, and want to kill them (although they say "destroy", since they don't think the androids are people).
The androids petition the Fedaration for asylum (or provisional membership- I can't remember), and Picard must hear arguments for and against that. Basicly, this comes down to "Are they people? are they alive? are they a race?" The Vemlans (an annoying [female]official and a male captain who hates the androids, but shows more sense; there would've been less of a stereotype if their genders had been reverced) make plausible arguments that can't be blown away easily. Their ideas are wrong, but beleivable. After all- this's what they've believed for centuries, so it has to be moderately plausible.
The Vemlan captain is a plausible character, who has both positive and negative qualities. The official is a jerk and too obsessed with vengeance and her own power.
The androids (who decide to be called "Spartacans" and people, instead of Vemlan androids because "android" means "a manlike object" and the historical figure Spartacus reminds them of themselves) have distinct personalities. For the most part they are positive, but they have flaws, as would be expected. The android captain (I can't remember his name; sorry)is mostly a good character, but he is willing to do almost anything for his peoples' survival. He plans to destroy the Enterprise if he has to, and the crew never find out. His wife and second-in-command is a bit gentler, but still developed some. The only other developed android (sorry, Spartacan) character is Maran, the librarian, who has a friendship/romance with Data. I like her; she talks with him about why he immitates humans, and if he should try to make his own way of doing things instead.
The interactions among the Enterprise crew were believable- I don't remember all, but Data and Geordi's friendship was there. The Enterprise people aren't paragons in this story- they're people. Picard is suspicious, and Data fails to win over hte Vemlan captain.
Also, in the debate, everyone had valid points. Picard brought up the Borg, and along wiht the question of "Are the androids a race?" he said, the same question could be asked of the Borg. Crusher asked if they could be considered a race since they needed a labrotory to reproduce. Ultimately she thought that the Spartacans were people, but not a race. The Vemlan captain's opinions had to do with experiance and emotion.
My only problems were a) it was stiff in places- but that's Next Generation, period and b) if Data is the only successful android in the Fedaration, after many tries- how did these other people, with less advanced technology, manage to mass-produce them?
That aside, it's a great book. It ends well, but not perfectly. The Vemlans don't change their minds (well, the captain decides to rebel)and it's possible that the Spartacans won't be accepted into the Fedaration. I like the realism of that imperfection, within a satisfying conclusion.