This book is less fanservicey than Genefather was by this point [halfway through]
If we don't get a necron lady's head in a box, as a relic weapon, then what's the point of these books?
The scifi conceits are much, much zanier than the previous title presented.
One of the POV characters is unusually Heresy-coded, being comissioned to faithfully document historic events. I am a little surprised that such figures don't get rolled into tabletop mission rules as extractible NPCs [for standard 2k games, I know that boarding action/kill team can have them]
Cawl would absolutely bamboozle the Emperor Undying if they crossed paths. Necrolord Prime would be amazed at the thanergy-free immortality of the Prime Conduit, while being impressed in turn by the institutional stability and comprehensive reach of the House crusades. Buuuuuut our techpriest-turned-metallic-dragon would catch onto the pettiness that underlies that whole project and thereby be fatally turned to disgust.
The Iron Warrior warsmith is not particularly charming thus far. He's certainly not the equal of Bile or a random Night Lord.
I SHOULD be more upset that an Ultramarine is here in the book when it could be practically anyone, but I suspect that change was required to hang more Plot onto [500worlds, I guess]