I very much enjoyed this book. I've read some of the author's short fiction in Interzone and was very impressed by it. I knew it had an Aztec setting and wasn't sure quite what to expect, I did Aztecs in school when I was 10, but it's an area and a period I know little about, so it was interesting to read about. There are all sorts of little details throughout that gave a good idea of how life was lived. The short stories I've read were set in an alternate-future with Aztec and Chinese empires in space, so I think I was initially expecting something more science fictional. I soon got into the historical in setting, and was interested to read about the magic wielded by priests and gods. I don't know Aztec myths, so I can't comment on that side of things, but the rules and magic all seemed consistent and worked with the setting. There was a good bibliography at the back of the book, and I recently got a free book about Mesoamerican art I shall look through.
The book is told from first person point of view by Acatl, who is a dedicated, honest man, but not a go-getter and weighed down with familial regrets and some resentment towards his successful brother. I found him to be mostly sympathetic, though there were occasions when you could see why his sister and deputy were so fed up with him. I found various of his character flaws familiar, so I identified with him more than some of the more action-based characters that can be found in the genre.
The only part of the book I found difficult were the names, which I didn't always know how to pronounce. However this wasn't really a problem as I'm not talking about the book out loud. Although I was curious about the sounds I'm actually glad there wasn't anything like a pronunciation guide.