As much as I enjoyed the final book in Kowal's Glamourist Histories, I was still iffy about reading her in Regency England because I spend too much time there. Kowal is at her best outside of the drawing room, taking her research and giving it room to expand.
Basically, this book seriously played to her strengths. The idea was delightfully clever, the execution was excellent, the story had me guessing and thinking I knew what was going on, but now how it would happen. And Tolkien made an appearance because of course he did.
Also, is Kowal contractually obligated to include a Doctor Who reference in every book? Not that I'm complaining or anything.