One of the things about sequels is that they must live up to the legacy of their predecessor. This is true in movies, but just as true in books as well.
One thing that can be said about the universe Simmons creates is that it is interesting, but incomplete. In this setting, we have technologically advanced post humans posing as Greek gods ("Any sufficiently advanced technology is indistinguishable from magic" or item three of Clarke's Three Laws), but we really never learn why they are posing as Gods, or even why Greek gods and not some other pantheon. And while Sebetos, Ariel, Prospero, and Caliban get sufficient fleshing out, the fate of Sebetos is never really developed (it just seems to leave ...was it sated on human misery? Scared away by the moravecs? Got bored?).
Nonetheless, Olympos still maintains a good pace and an engaging book. The ending is suitably happy, though one of the elements involving an early '60s (apparently) role-play of sex in the back seat of a teen-ager's car, interrupted by the apparent nuclear annihilation of a city seemed to serve little purpose (other than to say these far future post-humans have a poor grasp of history, unless it was some veiled suggestion of reality hopping of some sort...), and could have been more straight forward.
In the end, if you're looking for some unusual SF, Illium-Olympos might be something to look at.