At its core is the author's conceptualization of one path to superintelligence, where the human mind with all its emotional and cognitive human quirks is transposed into a quantum computer powered web that is allowed to be modified by the conscious/subconscious minds that are uploaded into it. What emerges is what was there to begin with in the minds of those who built it: a world like ours, with fantastic creatures and complex story arcs.
With time jumps reminiscent of Seven Eves and an immortal character that can be found in several of his books spanning centuries of time, he weaves together an entertaining story moving to a Tolkien like final battle.
Beneath that is an profoundly exixtential question: what would the afterlife look like if its structure were the product of human minds?