This seems like a short story expanded to a novella or short novel. Interesting (and complete) world design, religious oppression taken to an extreme. No real action in the first half, though. The second half is a good story, with elements of adventure and intrigue at the personal and government scale, and works fairly well.

Tried to find exactly why this book was banned, and only found the statement: "An exploration of alien sex so explicit it was one of the most banned books of it's time."

The only thing explicit is the biological description of how a species reproduces - unless it is the idea of sex with lights on and eyes wide open.

Easily a four or five star short story that suffers with expansion. Still a very quick read.