I really enjoyed this book's steampunk take on the French monarchy. The science fantasy aspects were very cool. Also, because I love art history, it was very neat to have main characters who were artists (including some that I've studied!) Honestly, just living in this world was my favorite thing about this book, thinking about what it would be like to live in that time--and how the presence of quasi-magical cyborg monarchs would change things. That's a pretty original counterfactual, and it was definitely interesting to explore!
The story itself wasn't as compelling to me. I particularly found the main character, John's, sort of misogynist attitude to be challenging (though certainly appropriate for the period). He very much idealizes his love interest, a beautiful girl who he barely knows but likes because she seems innocent and pure, and then is disgusted by her when she can't live up to those standards. Although probably an accurate way to depict the attitudes of the time, that made it hard to want to spend much time with this character, particularly towards the end of the book. On the other hand, Artemisia, the lady Scientist, ROCKS.
This is a fun and original idea, and the prose is great.