These books are complicated: they retell the classic Greek stories, focussing mainly on the Gods and the besieging of Troy, but they also throw in some Shakespeare, invented aliens, futuristic devices, and the whole thing is glued together by quantum theory.  Simmons would have us believe that quantum theory supports the principle that if human genius has invented somewhere or something, then that somewhere or something actually exists.
   The Greek tales become railroaded; the humans unite and turn on the Gods; Shakespearean and other monsters turn up to annihilate what is left of humanity; a large number of disparate characters go about having various adventures (a lot of them are killed or almost killed, but return via miraculous futuristic technology). Eventually the various adventurers meet up and the story develops into a straightforward Us (humans) against Them (aliens).  But it takes an awful long time for the storylines to crystallise out into a recognisable form.
   Simmons obviously knows what he’s talking about, and I’m quite sure there are lots of references in the book that I missed.  I probably missed some of the humour too – though I did pick up on some of it, and I particularly liked Helen of Troy getting a sore throat trying to emulate Zeus’ god-like roar.  I think I would recommend the books to anyone that asked, but only just.  Why only just?  Because they are, in my opinion, a little over-complicated.  I would have welcomed a bit more of a clue as to what was going on at an earlier stage – in the first book, for example.  And because, although lots of dire things happened throughout, I never empathised with any of the characters.  I never found myself anxious as to how or if they were going to survive.  But still, despite these flaws, both Ilium and Olympos are worth a read.