Soulless - Gail Carriger

Vampires (whose social structure resembles that of bees), werewolves, Victorian fashion and mores, mad scientist conspiracies, a dash of steampunk and some really steamy makeout scenes mixed together with a touch of the Mister Darcy Syndrome makes for an interesting and very entertaining novel by Gail Carriger.
This is a great book to read one chapter at a time, since the story is easy to slip in and out of. Plus, since Alexia Tarabotti - the awesome, intelligent, scientifically curious and strong-willed main character - seems to be mildly amnesiac about pretty important plot elements, there are some reminders about the relevant plot points during each chapter. It is, however, pretty hard to put down the book since all the chapter separations seem to occur right in the middle of fascinating, important, or downright steamy scenes.
After the epilogue is over and the story proper is done with, there's this interview of the author in which one answer pretty much sums up everything that's great about this genre-rich novel:

Soulless has such a clever melding of alternate history, romance, and the supernatural. How did you derive the idea for this novel? I knew I wanted to write urban fantasy, and there's one thing I've never been able to understand in the genre: if immortals were mucking about, wouldn't they have been mucking about for a very long time? A speculation arose: what if all those strange and unexplainable bends in history were the result of supernatural interference? At which point I asked myself, what's the weirdest most eccentric historical phenomenon of them all? Answer: the Great British Empire. Clearly, one tiny little island could only conquer half the known world with supernatural aid. Those absurd Victorian manners and ridiculous fashions were obviously dictated by vampires. And, without a doubt, the British army regimental system functioned on werewolf pack dynamics. Of course, as soon as I started scribbling away about a land of bustles and top hats, romance and comedy had to enter the fray. I mean to say, bustles! Then I tossed nineteenth-century science into the mix and realized that if the Victorians were studying vampires and werewolves (which they would do, if they knew about them), not to mention developing weapons against them, technology would have evolved differently. Enter a sprinkling of steampunk, and suddenly, I was juggling more subgenres than Ivy has ugly hats! But then again, you can never have too many hats.

Who is Ivy, you ask - well just read the book, would you?