Based on what I've read in this thread, the 40k license is being severely underestimated and I'm going to try very hard not to burn up.
The appeal is that no matter your personal philosophy, of war or what makes a good soldier, there's a race in 40k that caters to it. Personally I've always enjoyed a specialist approach, so I love the Eldar, beings whose long life has caused them to refine themselves almost to the point of stagnation. By the same merit, there is such a deep pool of potential in terms of varied philosophy and methods that you can tell the same story from seven different points of view and still be interesting, sometimes even within the same race. It's not like you are going to make a hit, suck it dry for two sequels and then have to start whoring out the license in order to move the product. *cough*
OT - My prediction is that this movie will indeed blow. Why? Two reasons: It has the "straight to DVD" stamp of death on it. Second, it's very difficult to cross mediums, and it requires a lot of ingenuity and funding to do so, neither of which are showing so far. Although, the worst they can do is spit out 70 minutes of slop with -+15 minutes of nice visuals.
However, that being said there are plenty of WH40k based shorts out there already, filled with just action, mayhem and WH mythos that you can watch for free. So why the hell would you half-ass a movie attempt? Aside from the hatred of money of course. Oh, and whoring.