What is a novel? I suggest we understand the novel to be an attempt to develop and explore an idea through the application of various literary techniques to a collection of narratives. While at their heart narratives are simply sets of events ordered and related through the unifying sock-puppet of the 'character', they are different from mere anecdotes in that they involve at least one character, the protagonist, changing, and perhaps growing.
Everyone should be familiar with the traditional narrative structure of a protagonist going on a journey, away from the familiar, encountering other characters, and encountering a series of crises, the last of which is the climactic crisis that allows the protagonist to either return to the state of normalcy, or to, upon denouement, settle into the new world defined by the idea or hook of the novel.
So in the sense of a series of events involving characters, Dan Abnett's Know No Fear succeeds in being a novel. Otherwise it fails, and rather spectacularly by comparison to Abnett's previous Horus Heresy novels such as Horus Rising and Prospero Burns. It lacks the character development of Garviel Loken and Kasper Hawser, respectively, or indeed character to develop. It fails to convey anything about the nature of the Space Marines and Primarchs involved, or about the nature of conflict, or really anything more than the fact that war in the 30th millennium involves short periods of people talking like morons think intelligent people might talk, and long and extraordinarily dull periods of fighting.
There's some development alluded to in the parts about a certain Contemptor Dreadnought, but both that character and its role in the novel seem completely superfluous. Which is interesting, because in the similar war-story Titanicus Abnett adeptly juggled the character development of a similar-sized host of characters, as well as a similar-sized host of faceless villains whose role it is to die easily and make the good guys look...good. Which is to say that the villains, the Word Bearers, are two dimensional in the extreme, and the heroes are perhaps worse.
Which isn't to say that it's as bad as the latest interminable and shockingly dull turd by Graham McNeill, The Outcast Dead, but it got close at times and I think I only finished it because I was expecting something to happen, some sort of click where the disparate elements of the story came together to make the events in the novel mean something. Particularly appalling was the scene whereby Roboute Guilliman leads a teleport assault on Kor Phaeron's captured command bunker, where Guilliman takes apart a host of Word Bearers, and pages later is almost killed by Kor Phaeron with apparent ease, only Phaeron's moustache-twirling villainy prevents Guilliman's disappointing death, and having his own heart ripped out in turn doesn't seem to be that much of an inconvenience either.
Stuff happens, rather a lot of it depending on one either having read previous novels, or ignored the events of previous novels, depending on the page, and once it's over, well, I regret having bought the hardcopy before reading it. I could practically hear the dice rolling during what I suppose I should grit my teeth and call 'action sequences', although I get the sense that the cover-scene, possibly the only reason for the novel existing, was accompanied by squelching noises rather than the clatter of dice...
Which isn't to say that people won't enjoy reading this novel. Just that people buying this novel looking for something similar to the three other works by Abnett that I've mentioned are going to be grossly disappointed. In its defense, however, I should give a nod to the high-quality heavyweight paper on which the novel is printed. Unfortunately the quality of the writing was more appropriate to a cheaper, and perhaps softer, stock.