For starters I should mention that I have never read any of the Dylan Dog comics... nor had I ever heard of the comic series prior to seeing a trailer for the movie. Heck it as by sheer accident that I learned of the movie itself actually.
The first time I saw any information about the movie was due to a floor-stand advertisement for the film at a local theater. Prior to that I am not sure I had even seen a trailer for the film. After a few weeks going by, I finally decided to look up information on the movie (as it was already out by then) and found the trailer for the film to be rather enjoyable.
To me the trailer was reminiscent of a more comical version of something like Anita Blake. The trailer looked cool enough to decide to see the movie; however I did a little research about the film beforehand. Much to my surprise I discovered that it was based on a very popular series of comics that have sold well across the pond.
As for the movie itself, I thoroughly enjoyed it. Being generally unfamiliar with the source material I found it to be a rather interesting take on undead and other creatures living among humans. A shame the movie was not advertised a bit more, it could have drawn more folk to the theaters.
My biggest complaint about the film, aside from lack of advertising, is that it felt like a very amateur project. Sure the movie was good and enjoyable, but it did not feel like something that was worthy of putting up on the big screen; had a feel of something more suitable for a direct to DVD release or a TV movie.
The ending of the movie could have used some work. It felt rushed.