I liked the book very much. But I have some thoughts...
The Ultramarines is my favorite chapter. I love the way the HH-series has described RG but for one thing. Isn't RG a master strategist? BftA the Ultras doesn't show much strength in that area, KnF is purely luck that the Ultras manages to turn the game around. And in Betrayer... I miss some kind of sign how RG thinks in the end. If he plans the attack, well, it's not that impressive... the World Eaters kicks their arse in strategy. When will we experience RG genius in the HH series!?
/ from Sweden, where the Space Wolves live