I can't say I'm hooked per se.
It's one of may games I play.
I like the citadel minis: collecting, assembling and painting minis are really what I'm "hooked" on.
The game?
Meh.
I love the flavor-text and fluff. I love the idea of playing out battles like what is in the novels. Of course, what's in the novels and flavor-text has little to do with the game.
The Game is actually a set of rules, to be used to the letter and the use of those rules in the most effective manner is called "tactics". The game is competitive, the goal is to win.
I'd have to say that I love Warhammer 40,000, but am not hooked on playing the game. I play occasionally, with folks who are more interested in playing a game, having fun in a Warhammer 40k universe...not necissarily strictly playing Warhammer 40,000 4th Edition. Does that make any sense?
I tend to play 40k with guys who are friendly players who are more interested in the fluff and flavor-text than the strict interpretations and application of the rules.