Almost too fluffy for words. Its saving grace is that it knows this, and never for a moment takes itself seriously. (It also understands that steampunk is, at heart, a visual aesthetic. Descriptions of vast arrays of gears and valves abound, but the book wisely stays away from attempts to explain how the fantastical devices actually work. Even the characters seem to keep them around mainly for decoration and amusement.)
The downside? I don't have much patience for growly, alpha-male romance. (And if I do happen to be in the mood, I'd rather go all out with the fluff and absurdity and dig up the Black Jewels trilogy.) If that's your thing, you'll probably love it. Me, I was rooting for the mild-mannered scientist the whole way through.