This was my favourite book of 2014, and now that the sequel has finally come out, I reread it in preparation for the next book. By now, I have lent it to so many people that the glitter on the cover has mostly rubbed off, but the content is still amazing. 
I love the entire idea of the Checquy, and the wider concept of the underground magical society hiding behind mundane human life. The amnesia plot is done really well, and the worldbuilding is amazing. It never feels strange if suddenly there's a future-telling duck, it is simply accepted as being within the established realm of the possible in the Checquy's world. Myfanwy Thomas is a really sympathetic protagonist, and allowing the reader, through her, to discover the Checquy slowly, yet from within, as an already established organisation, makes the world the author sets up seem organic and almost independent from the protagonist and the plot, as though it would exist regardless of whether this book had been written.