To be honest, I was pretty much lost on the science part of the story Dan Simmons was spinning in "Ilium" from the very beginning and when I picked up "Olympos" to read it was not in the hope that I would be able to catch up in that regard. By the time I finished the 735-page book I had really assumed that I just did not understand the science and how the three main plotlines of this sprawling narrative came together in the end. However, seeing all these reviews bemoaning a coherent conclusion that ties up all of the major threads leads me to believe that is not just my lack of understanding of quantum physics and the like that was why I was not really sure what it all meant in the end.
Certainly these two novels constitute an ambitious effort by Simmons. I was attracted to "Ilium" because I teach Classical Greek and Roman Mythology, look for any opportunity to teach Homer's "Iliad," and am even working on my own retelling of the Trojan War on the off chance that I can actually write something besides instructor's notes and reviews. So I found the idea of posthumans masquerading as the Greek gods, living on Mars, and playing games with the real Trojan War, rather compelling because Simmons was using hard (and futuristic) science to duplicate the powers of the gods. Besides, obviously I was going to identify with Thomas Hockenberry, the classics professor who had been resurrected as a scholic and not because he ends up in the bed of Helen of Troy (I find Andromache to be a lot more attractive as a human being and what would Cassandra think of somebody who actually believed her?).
But Simmons is not content to combine up Greek epic poetry and quantum physics, but also throws in Shakespeare's play "The Tempest" and even more literature into the mix. If anything, the attempt is already overly ambitious at that point and we still have all of those additional elements like the moravecs and voynix on the science fiction side of the equation. I end up thinking that more would be less because all of this is too much. Maybe the second time through I will be able to better pick up how it all fits together better, but right now that idea is rather daunting.
Speaking as a student of mythology I will say that I really liked how Simmons played out his revision of the "Iliad." I had noted in my review of "Ilium" that there was a point where clearly we were not in the "Iliad" anymore, so when Hockenberry noted that this was literarily the case because what was happening was from Virgil's "Aeneid," that was my biggest laugh in reading "Olympos." Beyond that I really liked the idea that the invulnerability of Achilles, son of Peleus, came not from being dipped in the River Styx or having his mortality burned away (except for the heel in both cases), but from being a quantum singularity who is "fated" to be killed by Paris (and also by not being the son of Peleus). Once Paris is dead, Achilles is doing well. I also liked the scientific explanation for why he falls hoplessly in love with the Amazon Queen Penthesilea and what Achilles does about that love after he kills her (I really liked the idea that Penthesilea is armed with the knowledge of Achilles' fatal flaw and realizes at the key moment that she does not know WHICH heel to strike).
Ultimately the problem for me is simply that I never cared about any chapter that did not have Achilles, Hockenberry, or the gods in it (I hung in there with Odysseus for a while, but the more he became Noman it seemed the less I was interested). As interested as I was in the parts playing with mythology I would find myself zoning out way too often while reading the other parts of the novel. Since only one of the three worked for me and it really did not come together in a way that completed a sense of wonder at the massive narrative, that became the logic by which I came up with my rating for this book. I still think "Olympos" is worth reading, especially after you have invested time in "Ilium," but also because of what he does in making the "Iliad" his own.