A tale told by an idiot, full of sound and fury, signifying nothing.

All right, Iain Banks is not an idiot.  You can tell by the way he writes that he’s actually quite intelligent.  Here’s the deal: in the far-distant future, humans (or at least some species that looks a lot like us) have spread all over the galaxy in an anarchist utopia with easy FTL, strong AI, and near godlike technology.  They live in a postscarcity economy and the AIs do all the work, so ordinary citizens can do pretty much whatever they want.  One wonders why they bother to do anything at all.

Against this conflict-free backdrop, a minor diplomatic intrigue slowly develops over the course of the book on the planet of Sursamen.  Much late-night cavorting in nanotech bars and descriptions of planet-sized engineering projects ensues.  Eventually, the intrigue gets to the point where the whole planet is threatened and Djan Seriy Anaplian, secret agent, must save the day.  The ending is depressing all but one of the characters I like dies horrifically.  Even then, nothing that happens on Sursamen matters, because it is only one of literally hundreds of thousands of inhabited worlds in this universe.

Why did Banks bother to spend 600+ pages to tell us this?  Well, to show off the high-tech special effects.  If you like intricate, high-concept scientific wordplay, this book is for you, but if you were looking for plot, look elsewhere.