Let me start by saying the graphic novel and the film seem to share a name only. That being said, the world created in the film is actually pretty interesting. Two species always at war with each other (vampires and humans) vampires seem to have all the advantages save two: the sun, and the warrior priests. What impressed me the most about the story was the way in which the vampires are portrayed.
These are not your Transylvanian creepy aristocratic vampires, or your sparkly emo teenager vampires. These are hive-minded gollum-looking things with no eyes that move around like wild predators. The only thing truly explained in detail over time in the film is the vampire. I found the similarities to insects like bees and ants, and the links to popular vampire mythos fascinating. They have no eyes, they secrete stuff that helps build the hive, they sleep in crypts, they have a queen that lays egg sacs, sunlight kills them, they can turn victims into slaves. Very cool stuff. Much better than Edward, that fucking pansy.
This movie, while having some originality, really just blended a whole bunch of other original ideas together. The biggest influence, and the central plotline, was straight out of The Searchers with John Wayne. Elements of 1984, and the Unforgiven pop up also. They even borrow the "your father isn't who you think he is" bit from Star Wars and Golden Compass, but it's basically a Searchers remake, covered up and repackaged with vampires.
Which got me thinking, and then got me a little angry, especially after watching a trailer for the new Straw Dogs remake (even the movie posters are nearly identical), are there not any new movies to be made? Adapting films from books or comics doesn't bother me so much. Remaking a film that already was made, one that was already a classic and should stand forever as a good film on its own merit, that bothers me. Was Sam Peckinpaw's Straw Dogs not good enough? It was already an adaptation of The Seige of Trenchers Farm (by Gordon Williams).
Why couldn't Priest be a film actually based on the comic's true plotline? Why use the name as a vehicle for a Searchers remake? Why try and hide the fact that it is a Searchers remake in the first place? It would have been a good starting place for an entire new franchise of films, but instead it's a Western/ScienceFiction/Monster movie mashup that failed at the box office. So, now this cool reimagining of what a vampire could be, is going to be buried.