Mundane disclosure first: I have been a huge Iain (M) Banks fan for a long time, so I won't pretend full objectivity. In fact, had this been a new author's work it would have been a 5 star review. Banks novels set the bar so highly for me that I may be slightly more critical of them than I would be otherwise.
For fans of the Culture series, however, this is a worthy addition: not quite the best (Player of Games remains my all-time favourite, followed closely by Consider Phlebas and Look to Windward - the latter not shared by everyone, I know, and I also have a lot of time for Surface Detail). I found myself, however, looking for any opportunity to return to this whenever possible and, as so often with Banks's novels, am disappointed it's over.
The humour of the Minds is sparkling in this book - Banks's gods in the machines (literally) always remind me of slightly squabbling Olympians, with all those human foibles the Greeks projected onto their deities. However, there is one element that does grate with regard to the book: lots of people die in this novel - including some significant characters (no spoilers) - but the culture of the, ah, Culture is such that the major ones are pretty much all backed up (there is one exception to this, but even that is not, in the end, completely final). I offer this in contrast to the (early) George R R Martin novels, where you come to feel greatly for major characters who then die. Gone. That's it - no coming back (and even Martin baulks at this in later novels). Banks seems to have written himself into a tight spot re. tragedy where the Culture series appears unable to deal with it on the profoundest level. And yet, in Consider Phlebas I really felt the waste and tragedy of the Idiran war.
One note re. pricing: the 1 star "reviews" are extremely annoying, particularly as they are by people who have not read the fracking book! However, I do want to record a milder protest to the publishers. Publishers have to make money - sure - and the costs of production are much, much more than printing a book and distributing it, but I did feel ever so slightly ripped off reading this. Obviously Amazon is hugely discounting the hardback version, but I like reading novels on Kindle and wish they were in the same position to discount the ebook should they so desire. When I saw a new Banks coming out at this price, I thought I'd wait till it dropped. I held out for a day (more fool me, I guess!).
This latter comment has *not* influenced my star rating - in fact, I nearly made it 5 stars to counter the 1 star reviews. This is genuinely a 4 star book for me, though I do feel that unfortunately the price will put off a lot of readers who would really enjoy this novel.