So, yes, I take back what I said about Culture novels - they're actually good, even with all the idiosyncratic ideas characteristic of Banks. It is not a pure Hard Science Fiction like Greg Egan or even Stephen Baxter, but it is still a ultra high-tech society with amazing science, even if it is "wave of hand" in many cases, which Egan absolutely hates.
This book also starts with a medieval society, as several other Culture novels, which I am not a huge fan of - if I a wanted medieval novel, I'd go get one - and you have to wade through half a book of mediocre medieval+20th century guns prose to get to the good part. I never read any of the Banks' non-science fiction novels, but I suspect they are medieval too.
Anyways, the novel gets good about half-way and it continues to be good. The shell world Sursamen is front and center and we learn a lot about how it works and about its creators, the Involucra/The Veil and the destroyers of the Shellworlds, the Iln. We also learn about the Oct and the Altrudia, who have developed from parasites on the body of a 2km-long Xinthian Aeronathosaurus which lives in the core of Sursamen and is worshiped as its World-God.
We further learn about the Involved Optimae like the Nariscene and the Morthanveld, and of course, the Culture and its Special Circumstances section of Contact, which seems to be quite very involved in the affairs of the Galaxy and its inhabitants. The main protagonist, Anaplian, is a princess of the 8th level of Sursamen, of the Sarl, but moves to the Culture as a young woman and eventually becomes an operative of Special Circumstances. At the end she dies by sacrificing herself to kill the Iln machine which is generating enough anti-matter to destroy the entire shell world. Yes, I love spoilers!
Other characters, like Ferbin and Holse, remind a bit of Frodo and Samwise, and the parallel that Banks intentionally draws with The Lord of the Rings. There's murder and intrigue, and shitty people with power being shitty people with power, and Nameless City and Caude and flying beasts, and artificial water world built to enclose a small star and super intelligent aliens communicating by changing color of their spiniforms, and many other interesting things, because it is a very dense book, but the end feels a bit unsatisfying, as it ends abruptly and the bad guys are not explicitly punished. Still a good read. Four books to go to finish the entire Culture series!
