I don't know why, but the characters never got into my mind. There are only a few of them anyway, but somehow unlike 'Complicity' and 'the Business', "a song of stone" never worked the miracles Banks can do. The story is told by a castle owner, the narrator who writes to the woman he loves, who also figures in the book. But he also uses the 'you' for the castle, owned by his family for ages. The setting is the end of the war, a last struggle, the last few victims of senseless violence. Perhaps I should have read it more concentrated, but to me, not much is happening. We are left with the thoughts of the narrator, but they are not that interesting.
"An apocalyptic masterpiece" the Financial Times is quoted on the back cover, amongst praise from others. It's probably me then. I wouldn't go as far as to say it was a bad book, but perhaps my expectations were to high after enjoying the previous two too much. If you haven't read anything by him yet, you definitely should. I know there are plenty of sci-fi/fantasy fans around. He also publishes books in that genre under the name Iain M. Banks. As that is not my style, I shan't bother trying. Plenty of other books to go. Still a dozen to get to 100 this year.