This was every bit as delightful as I had hoped and expected. A light read, despite some tense happenings. A bit on the predictable side, but there were a still a couple twists, and I certainly couldn't predict the pitfalls in the house of mirrors, or the fun inventions - the kinds of elements that draw me to the steampunk genre.
I liked Nyssa as a resourceful, smart, and compassionate heroine. I very much look forward to reading more books about her - in fact I have already purchased the next two books, and will be reading them soon.
I'd say more about the secondary characters, but I don't want to let any spoilers slip, so let's just say that they were all well drawn and delightful, too.
Content rating would be PG-13, for some intense situations and a bit of violence, though it's not too graphic.