Did you see Constantine? Then you've seen Dylan Dog. I swear to god the writers read one Philip Marlowe novel, then Constantine, then said 'Fuck, we can do this!' and voila, Dylan Dog. Hell, both films even have Peter Stormare (and he steals the show in both) God love Brandon Routh, seems like the best guy in the history of ever, but he's in full on Superman mode here; quiet, desperate, tortured.
Never read the comic and now, don't really want to. Boo to Dylan Dog.