I would probably say this looks like fun ... if I didn't know the comics. They've changed so much, I don't even get how they can still call it "Dylan Dog". In the comics, Dylan is English and lives in London, not New Orleans. His sidekick isn't a zombie but a Groucho Marx-lookalike called, well, "Groucho". And the tone is much more early Dario Argento than Buffy the Vampire Slayer. The only thing the movie seems to have in common with the source material is that it is about a somewhat eccentric paranormal investigator with dark hair.
Of course, there is still a chance that the movie will end up being perfectly entertaining. But why make an adaptation of a specific comic book series if you're gonna change everything anyway?