Liked it, overall. I mean, I read it all in one day, so that's a good sign. Fun and polished and the first real steampunk I've read. 
 However, I felt like it was missing something. The story line was engaging but the plot seemed sort of incidental to the world building, and the world building itself was not nearly as detailed as I'd hoped. The characters are interesting but also a little too flat. Just because it's YA doesn't mean the characters can't be complicated or thoughtful. Plus the random paranormal creatures seemed just odd; I can see no real reason to have any of the characters be vampires or werewolves, unless it has something to do with Carriger's adult series -- and I understand that this YA series is a prequel of sorts for that, but I don't like feeling like I'm missing something important if I haven't read the "grown-up" version. 
 Overall the whole thing felt rather fluffy, which I don't actually mind. And I do look forward to reading the rest of the series, and perhaps the author's adult novels as well.