Coming from someone who owns every novel (minus the filthy xenos ones), I can honestly say:
1. The multiplayer is great - violent, fast, intense and what I would expect from a quick space marine conflict. The weapons seem a little unbalanced, but overall good.
2. The story might seem a little empty, but I think this stems from running through needless sections of map that are empty. I think they did this to impart a sense of awe at how large everything is in the WH40K verse.
3. I dislike their selection of the Ultramarines. I am very glad it was not Blood ravens however. They should have had a chapter with a little more character and personality.
Overall - excellent and well worth even the full price of the game.