For me it did, I struggled a lot in the early parts of the book because I didn't find Amadeus interesting (which is impressive because I like how the Mentors fight lol). I think Amadeus as a character was designed to contrast as much as possible with Spears first, then was fleshed out. IMO the story gets better as more characters are introduced and he becomes less of the focal point and grows a bit as a character.
The other part of the story that it took me awhile to figure out was who the villain is. The real challenge that the characters face in this story is isolation. In most 40k books there tends to be rival that a character needs to overcome whether by fighting them or in some cases figuring out how to work together with them. Spears does have those rivalries but being Isolated from the imperium and how they try to handle it is the real conflict.
Very good observation. This story is quite atypical for BL as there is no one who needs their face smashed in for the protagonists to prevail.
Instead they have to deal with their own sense of isolation, trauma, betrayal and search of purpose.
May not be everyone's cup of tea.
On a personal note, I was recovering from a minor surgery while reading the book, and certain parts resonated really deeply with what I felt at the time.