I recently reread this book after delving into Matter by the same author. Part of my motivation was to contrast the two. Matter, which I hadn't particularly enjoyed, shared a somewhat similar story with this one that I had adored in the past.
The narrative of this book is rather gimmicky, yet it functions effectively. There are alternating chapters. One set tells a straightforward space opera story, while the second set (differentiated by Roman numerals) is presented in antichronological order, revealing episodes from the main character's past. These episodes are often alluded to but not fully explained in the main story.
It succeeds because Banks skillfully measures how much to disclose and how much to keep concealed. He manages to make all the chapters engaging without demanding a mental shift from one set to the other. The overarching aim is to demonstrate how war can be both fascinating and attractive, perhaps even intrinsic to human nature, yet simultaneously evil and destructive. It also shows how an "enlightened" society still requires weapons and war to further its own aims or whims. Just like a weapon, the main character doesn't truly understand the how or the why. He simply knows what is expected of him and does his best from there.
Banks showcases the typical human response to war and weapons, a combination of horror and fascination in varying degrees, and uses it to illustrate a timeless story within a very well-crafted future tapestry.
As such, it is a perfect book for anyone willing to grapple with both the changes of a distant future and the folly of war.