The advantage that comic book to film conversions have over less conventional comic-style films is a rich backstory on which to draw both characters and scenarios. The disadvantage is that writers have to maintain a coherent storyline from such a wide source, while preferably keeping fans happy. This is the downfall of Hell Boy.
There are so many characters, interactions and plot details obviously lifted from the comic books that are either dealt with incidentally or completely skimmed over that, to someone who isn’t familiar with the material, it comes across as a sham of a film with no substance. This is a shame because there is obviously a good film in there, if only it had been better focussed. A shame.