Storyline: 4/5 
 Characters: 3/5 
 Writing Style: 3/5 
 World: 4/5 
 This will not be an objective review. I am already partial to Mr. Banks, you see; I'm a Culture fan. I enthusiastically continue to read because I like what the author has done through the previous nine titles in the series. I bask in the silhouette of grand worldbuilding, where immense civilizations and epic histories are hinted at over every horizon. Iain M. Banks does this like no other. I value speculative fiction of the sort that follows social, economic, and political ideas to their extremes. The Culture's post-scarcity, communist utopia give readers the opportunity to consider what we would do if we had every material comfort, long life, and a secure environment. I indulge in and soak up every detail of far future science fiction environments, eager to experience the future I'll never live to experience. Banks consistently offers a fine balance between the alienness implicit in such a future and a familiarity that keeps it relevant to us today. In those times when I'm honest with myself, I'll admit that I also delight in violence, reveling in that primal urge to test one's strength, ingenuity, and determination against another. The Hydrogen Sonata delivers, with Banks worrying alongside me that perhaps we indulge a little too far. Still, neither of us seek remedy. There is no other science fiction series that gives me these doses, in the right concentrations, and with such consistency. There is no science fiction series that I have enjoyed more. 
 My partiality now established, I do offer an amendment, a stipulation if you will. My favoritism is not without judgment or critique. Many a series author has led to me great heights only to later drop me in some crevice where lack of vision, loss of creativity, and monotony prevail, a place where they defy themselves. At the outset of the Hydrogen Sonata, then, Banks could indeed go wrong. There are series elements that I've long held in distaste. Banks is gruesome and lascivious (and sometimes gruesomely lascivious) with regularity. I've never particularly liked the AI voice of drones and ships. The storylines are often more erratic than is enjoyable. And out of every three thoughtfully worked descriptions there is long-running, incomprehensibly complicated, if not altogether grammatically incorrect, sentence. 
 This review, up to this point, could be about any Culture book or a review of the entire series. The reason for that is that the Hydrogen Sonata was an average Culture book. Not simply average as in of middling quality, but average as in having a middling variety of both the new and old. I rank it as fifth in the decalogy, bumping down the ninth-in-publication, Surface Details, to the bottom half. It could easily be reversed, Surface Details rounding out the top half and The Hydrogen Sonata at the top of the bottom. Much like Surface Details, Banks confronts a phenomenon that has previously been a side-issue in the universe, something that has minor relevance to past stories but which was never explained or developed. Unlike the other Culture books that I'd put in the top half, The Hydrogen Sonata never excels at anything. There is no defining and extravagant feature, no major contribution or development. It is simply good, though not great, throughout. The story was more straightforward than is typical for a Culture book. The excellent worldbuilding for which I revere him starts early. It was much more of a traditional space opera than the Culture series has presented in a long time, since Consider Phlebas (to which it is most similar). 
 A review of the final Culture book cannot end, of course, without expressing sadness over the premature passing of Iain M. Banks. Obviously family and friends carry the preponderance of grief, but the science fiction community definitely lost a great in 2013. If he had continued writing for another 20 years, publishing a Culture novel every 2 and a half years, we would have gotten eight more Culture books. I would have looked forward to every release and am sad to have it end. 
 My ranking of the series' ten, best to worst: 
 Player of Games 
 Excession 
 Look to Windward 
 Matter 
 The Hydrogen Sonata 
 Surface Details 
 Use of Weapons 
 Inversions 
 State of the Art 
 Consider Phlebas