I finished this one a few days ago, and decided to share about my thoughts. I know I do not do book reviews here as frequently as was once the case, and I miss them.
This started a bit slow. The opening 'act' so to speak, takes place on a cemetary world of no strategic importance, and even less plot significance. The learning curve is a bit steep as well, seeing as I am not exactly new to the universe, and still had difficulty keeping track of some of the factions and titles. For instance, I did not know what Blood Angels titles corresponded to what positions in other Chapters. Sanguinary priests, Reclusiarchs, etc. A little more detail about what each character's function was within the chapter might have been useful.
In all though, this was fairly well written, and an interesting story. The insidious plot is fairly straightforward, with no major twists or unforseen speed bumps. On the plus side, I was able to read this while biking and not have too much trouble keeping pace with the story, or coming back to it between workout sessions.
I recommend it for fans of the Warhammer 40k universe, and particularly the spat of New Blood angels fans from the new codex.