The world is well-developed and creative, especially the Darwinist living technology and the ways the two technology streams have clearly influenced one another. Seriously: it’s half Darwinpunk. That’s just awesome.The main characters are unsurprising but believable and sympathetic, even if Alek is a bit daft sometimes. The minor characters are entertaining, particularly a lady scientist who is exactly the kind of character we’re programmed to like. And we do, mostly—but it’s no surprise that other characters find her incredibly annoying. The plot moves along briskly, without major twists but with plenty of small surprises and clever details to keep it interesting.It’s the first in a series and doesn’t try to properly conclude, but it comes to a sensible stopping point; it’s generally a satisfying book, and Westerfeld has seeded plenty of fertile ground to explore in the next one.