I listened to the audiobook version and I feel like this helped a lot bc the narrator is amazing but also has very specific voices for each character, so it was easier to tell who was who.
I definitely enjoyed Nona the Ninth. It was really interesting to see the other characters from Nona’s point of view. I loved figuring out who was who when there were codenames etc being used. 
I feel like I don’t fully understand everything that’s happened right now, but that feels like a given with this series!
In comparison, for me, Gideon the Ninth was a solid 5 star, Harrow the Ninth was more a 4 star.