I found the start very confusing and disjointed. Three totally unrelated stories, one of the battle of Troy, a second robots on Io, and a third humans living on a reconstructed world with essentially no knowledge of their history or geography, and obnoxious mostly.
At the end, of course, the three pieces come together. However, I found that even so, much of it made little sense to me, as to the whys and wherefores.