"Leviathan" by Scott Westerfeld

"Prince Aleksander, would-be heir to the Austro-Hungarian throne, is on the run. His own people have turned on him. His title is worthless. All he has is a battletorn war machine and a loyal crew of men.
Deryn Sharp is a commoner, disguised as a boy in the British Air Service. She's a brilliant airman. But her secret is in constant danger of being discovered.
With World War I brewing, Alek and Deryn's paths cross in the most unexpected way…taking them on a fantastical, around-the-world adventure that will change both their lives forever"-goodreads

Leviathan is the first steampunk book I've read. (Note: I still wouldn't understand what steampunk IS if it weren't for: a) Angela who is awesome and kind of a steampunk specialist, b) to some extent, google, and c) this book.) I now understand the appeal. It's also the first novel by Scott Westerfeld that I've read besides Uglies, Pretties, and Specials (which was ages ago and I REALLY need to re-read them as I hardly remember anything except that they were amazing). If they hadn't proved his genius-- Leviathan would have!

First off, oh my gosh I need to talk about the illustrations. There are these really intricate, awesome, brilliant full page and half page illustrations throughout the book. These were both great to look at and good at explaining things. The 'clanker' machinery and the 'Darwinist' creatures were so bizarre that I couldn't quite picture them, but then the illustrations had me seeing them perfectly. So cool. Then another favorite bit for me was how it's both historical fiction and futuristic fiction seamlessly put together, which is the steampunk element, but it was so interesting to read about a World War II world in an alternate society and universe sort of way. I can't wait for those things to be explored more in Behemouth and Goliath, the other two books in the series (although Goliath hasn't come out yet). 

The only negative thing I have to say about this book is while Alek and Deryn are obviously different characters, genders, and very different personalities their thought processes seemed TOO similar sometimes. Also, something to note, although Leviathan seems to have been marketed as a YA book I'd say it could just as easily be enjoyed by a more middle-grade and younger audience-- it has something for pretty much everyone in a broad age range!