Stross sticks the landing here, I feel. For a series that he started way back in the early 2000s this has been quite the journey. I am inclined to say this is a strong 4.5.
Clearly he wanted to talk about revolutions and the first natural transfer of power. Throw the external pressures of a meddling alternate dimension USofA and an alien invasion from yet another dimension into the mix and you have quite the pressure cooker.
The various plot strands clipped along quite nicely and the resolution for these characters felt natural.
I have thoroughly enjoyed this series from start to finish, even with saying the series at the start is very different from the end.
The whole thing is a definite recommend from me.