My favourite among the Horus Heresy books up to now, as the Heresy has now kicked off and the backroom plotting is at least somewhat abetting towards the middle of this one.

Speaking for the overall series, I was a bit worried how having multiple authors writing the same story with the same main characters would turn out, but I have to say that my worries were misplaced. There's no weird "Change of Character" for the main characters between the different authors.