I’ve read book 2 of Terra Ignota and I’m writing up a second Notes Ignota bunch of posts – which hopefully won’t take as long but I’ve gone off on a few tangents (e.g. this war film is not actually relevant to the book or referenced by Ada Palmer https://en.wikipedia.org/wiki/Ill_Met_by_Moonlight_(film) ).
I’ll do a review after I finish the notes. However, yes, lots of things are clearer and yes, this is really the second half of one book that needs to be read as a whole to feel like you read a story. It’s not a conventional sequel but rather a completion of a plot. I assume the reasoning for the split was commercial – which is fair enough, authors and publishers want a book to succeed in multiple ways.
I can’t say that many of the debates about the book are resolved by reading the second half but the scope of those discussions become clearer. This particularly true with the issue of how gender is represented.