This is quite a long book for a first-person narrative. Bear's other novels of comparable length feature half a dozen characters, but here we have only one - Casseia Majumdar, Martian citizen, college student, ambassador to Earth, and Martian political hero. The central conflict, though it takes a while to get burning, is the Martian colonies' fight for independence from Earth.
But this isn't a violent book. For the most part it's a political struggle, and Bear does an excellent job of breathing life into a potentially slow-moving and drab story. His science, as always, is impeccable, from the terraforming process of Mars, to the genetically modified humans who Casseia meets on Earth.
It is a little slow in places (the scientific info dumps are a bit more ponderous than in others by Greg Bear), and for a while the story seems to lose its way, but this is compensated for by the general smoothness of Bear's writing, and the depth of his narrator's voice. Greg Bear is one of only a few science-fiction writers who knows how to create real, believable characters to match the science of his books.
He also manages to drag you into the story, once the tension really starts mounting. By the end, I was screaming at the injustices perpetrated by the imperialistic Earth government.