Closer to 3.5 than to 4.0, but in the end it wins me over. There's a lot of worldbuilding, tech and post-human philosophy here that's admirable but not necessarily thrilling (If we can create beings with human-equivalent intelligence, what does it say about us if we limit the intelligence we put in our creations?), especially since it takes place over literally millennia with some huge time skips and has characters that are nigh-immortal. But eventually, it builds to a finale that's both effective and thoughtworthy in its refusal to bow to pessimism.