I appreciate this series’s absolute willingness to be bananas and lean in to being a gendankenexperiment with a plot. 
And it’s also a trilogy about what it means to be People (human or even Human manifestly not sufficient for current purposes). 
The first is about sentience in a radically different body shape, the second takes the first book and combines that with distributed consciousness and then this is the obvious third stage of “what is sentience anyway”. 

I didn’t originally love the AuDHD birds especially as it became clear that Tchaikovsky was doing it on purpose. And, by the end, once the corvids started on

we’re not sentient but neither are any of the rest of you,

I was suddenly much more sold on them and what Tchaikovsky was doing with it. 
These books are hard to describe because they’re ALL about the weird and the what if. Thinking on character level it’s hard to talk about these books but this is one of the few series where the author’s choice to go worldbuilding and ideology instead of (rather than through) character still works for me. 
Some of that is because he does have some touchstone characters to carry the story. But much of it is Hudson’s narration. 
My one observation is that, in a way I find startling, he’s one of the few authors in the sff field that have interesting things to say but nothing about gender. And it’s notable by now in its absence because so much other stuff about culture is integral to these books.