I just finished reading Graham McNiell's Chapters Due, and all I can say is it is an Ultramarine players wet dream. It's taken six novels, but we finally get to see a conflict that pits the bulk of the Ultramarine's chapter against a ravening chaos horde intent on destroying Ultramar and everything great in the Imperium (yup, I am an ultramarine fanboy). For haters of Uriel Ventris, go back and reread the novels and look at them from a different perspective. Uriel is an atypical Ultramarine so that McNiell can actually show you what it means to be an Ultramarine by having the reader struggle with Uriel as he strives to figure it out. It's only in Courage and Honour that Uriel finally shows he gets it.
At first, I thought this novel was a little too ambitious, it depicts an sub sector wide conflict in smaller vignettes rather than in one big hole. The reader only sees snapshots. But by the end of the novel it comes together quite nicely, and might even have some foreshadowing for one of McNiell's Horus Heresy novels. Oh, and Honsou is in it too, his part takes up after the short story the "Skull Harvest" which is definitely worth reading if you haven't before you read this novel. All around, one of the best reads I've had since 1000 Sons.