I've been looking forward to reading this ever since enjoying An Instance of the Fingerpost, and I think I enjoyed it even more... like An Instance of the Fingerpost it involves multiple narratives, but with a different effect. Fingerpost contained four narratives presented consecutively, each giving a different perspective on the same event (a murder). There was a sense in which each narrative superceded the previous one, so that the final account of the murder seemed the most complete.
The Dream of Scipio is arranged differently. It contains the stories of three men living in the same area of France at different points in history, whose stories are connected by their relation to a philosophical manuscript and by their responses to the ethical problems they are confronted with. Rather than being presented consecutively, the three narratives are intermingled so that as the reader you find yourself following the outcomes of three stories at once. Partly because of this approach, The Dream of Scipio emphasises the common features of humans and human problems, whereas An Instance of the Fingerpost said more about the incommensurability of human experience, as its four narrators stood alienated and apart from each other, seemingly incapable of a viewpoint other than their own.
Each of the three men in The Dream of Scipio struggle with issues involving ideals, friendship and betrayal. One character is a Roman noble living in France as the Roman empire is crumbling, another is a Medieval poet living in the panic-stricken Europe of the Black Death, while the third is a French academic living in Vichy France during the occupation. The decisions they make are linked to and informed by a Neoplatonic text "The Dream of Scipio" written by the Roman noble. Because of this aspect, I found that discovering the different characters' final ethical position with regard to this text was more of a shock than uncovering the actual events involved in each story.