Campbell has a uniquely visual and imaginative prose style. His language is often metaphoric and his descriptions are detailed and interesting. He excels at stringing the reader along through a multitude of images, transitioning subtly from the ordinary, to the unusual, to the horrible. There are many scenes where protagonist Rose walks through the city, or down a street in the bad part of town, or along a path through a park. These 'walking' scenes mount and mount as Rose goes from watching the everyday to seeing creepy strangers watching her or amorphous horrors chasing after her. The biggest problem with this novel is that there are just too many of these scenes. Chapter after chapter, Rose is going somewhere and she begins to see things and she struggles internally to control herself and her emotions and it looks like she's going to be caught by something or see something, but then she escapes, and the reader never recieves the true confrontation (the payoff) he/she was looking for. Personally, I enjoy a scene that builds and builds upon itself until you are dying to know what is about to happen, but when the scenes builds and then fades, without that big payoff, it can be frustrating.
Despite its sometimes ponderous flow from chapter to chapter, "The Parasite" is still a very good book; it opens with a bang and concludes with a bang; it's the middle portion of the book that becomes a bit tedious. The book opens with Rose as a little girl trapped in a room with something horrible, something her friends summon with an oijaboard; it concludes with Rose's final confrontation with this dark being. The ending is fantastic, beautifully written and constructed, if a little predictable. I found I was bored with the book at points and worried it would have a less than satisfying ending, but I was excited when the "good stuff" finally came. The conclusion was perfect and made the book worthwhile. "The Parasite," in its entirety, feels like a short story that has been extended into novel length, with the real heart of the story split between the beginning of the book and the end.
All in all, "The Parasite" is a novel of internal struggle and self-discovery. The problem with any work of writing that spends too much time with a single character's internal and emotional struggles is that there is less story movement and action taking place than there probably should be. The cardinal rule of writing has always been "show, don't tell" whenever possible and Campbell does less characterization and plot advancement through action than he does through Rose's confused thoughts.
I recommend this book to hardcore fans of horror fiction, but not to your average reader. It has a predictable story line and the characters are not too interesting. It pays off through its element of psychological horror, but this element alone is not enough to hold your general readers attention.