Eisenhorn and Ravenor should make the list as required reading for Dark Heresy players, I agree.
They really did help build a lot of the fan interest for Dark Heresy early on, imo. Obviously the long term desire for a 'true' RPG (Inquisitor was nice, but with no in-built balance system for character creation, it relies heavily in the GM) was a big boon as well.
Though it did ruffle some feathers when people found out the game was geared around playing starting Acolytes, and not the close servants of the Inquisitor themself (or the Inquisitor), the likes of Harlon Nayl and Madame Bequin. I personally like the opportunity to build your character up.