I originally picked up Leviathan for a base and shallow reason: it has an amazing map.
You can tell a lot about a science fiction/fantasy book by its map. The map is an artifact of the world into which you're about to submerge, and one of the only physical representations of the book (aside from the cover art). Leviathan's map shows WWI-era Europe sketched in a warring mishmash of biology and technology. A Russian bear opens its maw to swallow the Austo-Hungarian machine of war. The amount of activity on the page shoots miles beyond the conventional restraints of geography or topography. This map spells out one unmistakable feature: strange conflict.
And the actual book fulfills this expectation nicely. Leviathan lands the reader at a sprint, wasting no time in upending the lives of two young protagonists on opposite sides of a burgeoning world war. Alek is a young noble of the Austro-Hungarian empire who embarks on a long journey in a massive, armored walker. Under normal circumstances, this would prove to be the dream of a young Clanker (mechanically-inclined person), but Alek is fleeing for his life before the burgeoning war consumes him as it did his parents.
On the other side of the battlefield is Deryn Sharp, a British would-be aeronaut who finds herself laboring on the airship "Leviathan," a hydrogen-breathing whale. Yes, an honest to mercy, "save the whales"-style whale. Deryn must masquerade as a young man in order to enlist in the military, so she spends much of the book hiding her identity in order to maintain her adventurous lifestyle.
The different technologies at play in this version of WWI underline Europe's cultural diversity, and facilitate as many complications as they do luxuries. This is a world where living trains and automobiles can breed. Through Deryn and Alek's points of view, the reader gets an accurate snapshot of the Clanker and Darwinist (biologically-inclined) cultures—how they operate their daily lives, their core values, and through what lens they view each other through.
For all of the details that Scott Westerfeld sets in place, Leviathan does amount to one big set-up that introduces future conflicts on a grander scale. The overall book fails to achieve much detail about the actual war or some of the parties who seek to perpetuate it, fixating instead on characters who don't feel entirely invested. With that said, there are sequels on the shelves already. Leviathan is the author setting pieces on a board for the subsequent books to play out.
No doubt that impressive map will need some revision. Leviathan promises that the strange world is soon to get even stranger as beast and machine face each other on a worldwide battleground.
What would you be: Clanker or Darwinist?