For the plot description I shamelessly plagiarized the first two and a half sentences of the official book description. The Earth no longer rotates. Science rules the dayside of the globe. Magic rules the World of Night. Jack of Shadows was a thief whose magic was strongly connected with shadows. In other worlds, he could not do any magic in complete absence of them. He was caught in the beginning of the book and executed. Being a supernatural being he had several lives, just like an ordinary cat.
He came back and sought revenge.
I am a big fan of Zelazny. I keep saying that even his minor efforts deserve 3 stars. This looks like one of them. The beginning was quite good; it slowed down by about one third in the book, but still remain decent until the second half. At that point I had to ask myself, "Who the heck wrote this part and why did the Grand Master of science fiction and fantasy let him/her destroy his work???" The very end became quite good - probably the best part, but at that time it was way too late.
Add to this the fact that during the bad part of the book I stopped caring about Jack and his fate and you will understand why I gave one of my all-time favorite science fiction writers only 3 stars this time. It is still not a waste of time by any means, but please if you are not familiar with Zelazny do not start your acquaintance with him with this novel. It has excellent ideas, but the execution really lacked.
At this point I have to recycle the first image I used here to show my face when I finished this novel:
Boy, was I grumpy!