He's also a horror writer, which I suspect means whatever is inside his head is pretty scary too. (His book is Back Roads and Frontal Lobes. You should buy it.) However, in this film, which is based on an HP Lovecraft story, he's subtly terrifying. I wouldn't want to meet him in an abandoned house.
Now that you've watched the film, I'd also like to mention that I had not watched this movie before I wrote my post last night about looking up at the ceiling when a drop of blood fell on the counter. I felt an unpleasant shiver go through my entire body when I saw the end of the film, along with a slight sense of justification for having looked at the ceiling first.