Much more going on in this third book, which I really liked. More big events and especially more explanations of the history of the world.
It reminds me of a college class where the lectures were pretty boring but then one day the lecture involved some real-world uses for the stuff we were studying (how some industrial plants use huge inductors to fix their power factor and decrease their electricity bill). I told the professor that I really enjoyed the lecture that day, which he probably already knew because I wasn't nodding off in the back of class...shame. And he responded that you have to lay a little theoretical foundation so that you can understand the exciting real-world stuff. I see a similar parallel here where the first two books were good enough but sometime frustrating, and this one was the big payoff.
After finishing the second book I read some news articles about the "puppies" factions attempting to influence the Hugo voting around the times that these three novels were coming out. Definitely an unfortunate series of events!
I found myself questioning the wisdom of letting the Hugo winners list heavily influence my selection of reading...maybe populism isn't necessarily the best indicator of quality (to be clear, nothing against this trilogy in particular). But on the flip side, I can remember having sympathized with criticisms of other awards (Oscars or similar?) that are selected by industry members, thinking that a group of insiders like that may not be very representative of my interests as a consumer.