Could have been much better.
The first few levels where you fight on the planet against Imperium Space Marines and Guard are nicely done, they feel like a battlefield with much going on. Trenches with tanks driving overhead, explosions that were threatening to you and forced you to find cover were just a few things that made the experience great. But aftert that the luster wears off, and the game becomes a point and shoot repetition. The few levels afterwords that bring a WH40K feeling to the game are scattered, and most of the time you spend looking for keys or running through rooms.
Overall the game was a one hit wonder, pretty decent for a one run shoot-and-scoot campain but afterwords boring and drool.