Where to start.
OK. I liked this book. A lot. It's on my regular re-read list.
It features a universe where death and life are controlled by two poles, the House of the Dead, run by Anubis, and the House of Life, run Osiris. Anubis and Osiris cooperate and compete at the same time. Anubis has gotten ready an emissary, who he has been training for a thousand years, to kill his greatest enemy.
Without getting into spoilers, let's just say that things do not go as planned :)
Roger Zelazny wrote this book with an amazing stylistic touch. Many of the concepts he included were later picked up by other writers, like the various prayers spoken by Madrak, one of the major characters, of which 'The Possibly Proper Death Litany' is a fantastic example:
It can be argued that this is one of the most influential Science Fiction books ever written. It certainly is one of the most beautifully written.