Consider Phlebas is Ian (M.) Banks' first science fiction novel, and his first set in the extended universe of interstellar civilizations, most prominently one called simply "the Culture." The book focuses on Bora Horza Gobuchul, a spy and agent for the Iridians, who are at war with the Culture. Borza is humanoid, and provides the narration with an accessible entrance-from-the-outside, introducing us readers to the Culture with a critical eye. (He is, after all, voluntarily fighting a war against them, even though he is not Iridian.)
The Culture are a utopia, a moneyless post-scarcity society of plenty dedicated to freedom, fairness, pleasure, and interesting problems; it is managed with a light touch by (sentient) superintelligent computers. Horza sees this as a dystopia, fears and hates the computer intelligences; he argues with his actions and words that the Iridians --- a warlike, three-legged species of keratin-plate-covered giants who are religious fanatics --- are better than, or at least not as bad as, the Culture. It's an interesting authorial approach, since obviously readers will sympathize with the humans in the Culture, and probably prefer their well-managed, worry-free utopia over the Iridians, who are pretty horrible.
The Iridians keep slaves, and are not sentimental, and view even useful humanoid allies like Horza as subordinate not-quite-people. ("What they must feel for the swarming biped tribes of humankind! ... We are nothing to them: mere biomatons" p. 304) But they prefer biological life to computational, and that is enough to motivate Horza through the many disasters, emergency decompressions, painful beatings, and existential crises that he undergoes in the course of the novel.
I like it. Banks is a phenomenal writer --- I read his very disturbing The Wasp Factory years ago and its vivid horrors are forever burned into my brain. The narrative picks a delicate path across interstellar civilizations, giving enough detail to really challenge the imagination without bogging down in endless exposition. Cool ideas that could be the focal point of entire novels are used as background dressing for chapters or even single scenes. The novel's title comes from T. S. Eliot's The Waste Land, a line I've never understood and can't say I understand better after the novel. But I like both works, so their linkage at some fundamental level in the Banks' mind is like a savory nugget, that I can pleasantly return to musing about in my free time.
I unreservedly recommend this book, and will keep you updated with the joys of the rest of the Culture books as I methodically devour them during my commutes.
This post's theme word is noosphere, "the sum of human knowledge, thought, and culture." The Culture's noosphere is replete with curiosities, mysteries, and in-jokes.