This series was most interesting for its three rival galactic empires: you had the hyper-capitalist society which casually discards the poor and disenfranchised; the religious theocracy where believers live happy, carefree lives but dissidents are turned into mind-controlled slaves; and the military empire run as a brutal meritocracy.
There were protagonists from each one, and through them we saw that all of their societies were equally repugnant to one another. The characters themselves all had heroic traits, but none of them were, strictly speaking, "good guys" either. This gave the story a wonderfully murky morality, as you could never be sure who you wanted to root for.
The overarching plot, however, of ancient godlike beings frozen in stasis, waiting to be unleashed on the galaxy, took a long time to develop.