The basic story is simple: Two guys walking across Europe run across some ruins near a large pit and find a book detailing the horrors that occured nearby. The nature of the horrors, however, are complex and disturbing. They include dreams that seem to be more real than reality, abominations that humans should never set their eyes upon, and a grand, cosmic evil that wants to use trespassers as a gateway to the human race. As with Lovecraft, you probably won't understand everything, asking questions like "What's so bad about a cloud in the sky?" but that's thinking too much. The point here is to feel the fear that the characters face, that fear of the unknown, of the immutable, of that which cannot be explained or contained. It's scary because it's a person trapped in a house with something that completely transcends humanity. It is madness and insanity. It is what should not be.
Since this is a comic book, art is important, and while you might dislike the art at first, after a while, you should realize that the art isn't supposed to be pretty or awe-inspiring. After that, you should like the art just fine. It does a good job of making things feel, well, wrong. The art isn't bad; it's simply not what you usually see in a comic. But this is a horror story, after all. It'd be bad if this looked like an issue of Superman or Captain America. Just go into it not expecting it to look cartooney or completely realistic. (Sorry if that isn't helpful. I'm not a big art person.)
I highly recommend this comic. It is a good read that will stay with you, as long as you have an open mind and are willing to think deeply about things. And maybe, it will turn you onto a horror author that most people have forgotten but who does deserve to be recognized.