Like many things, I came to this series late and primarily due to the Showtime TV show. The concept of a serial killer who only preys on bad people intrigued me and I was happy to see that the show delivered on that promise. I quickly read the second volume and just recently finished reading this one.
First off, there are some differences between the book and the show as there should be. I won't go into the plot differences (so as not to 'spoil' the books for anyone who hasn't read them yet) but the stylistic difference is quite major. Like the show, the books are written from Dexter's viewpoint as he goes about his life, killing bad guys and basically trying not to get caught. The narrative in the first two is basic first person and we see the world and the stories through Dexter's eyes. This changes in the third book.
A new narrator is brought in for sections of the book as Dexter becomes hunted by something that could be more than just another serial killer. While building tension, this becomes quite bothersome as Dexter is the star of the book and I disliked any time the attention was not on him. In addition, we are given a bit more information as to the nature of Dexter's "Dark Passenger" who we are told is the part of Dexter that truly commits the murders. I disliked the fact that the Dark Passenger is not featured much in this third book and that the explanation for it tends to absolve Dexter of his part in the killings. To me, this was a mistake and serves to make Dexter more like other serial killers and less unique. In a sense, it excuses Dexter of responsability for his actions. As the plot is intricately tied into this concept, I found it to be less compelling than the other novels. Even though the killer(s) are supposed to be far more primal, I felt them to be far less interesting than the Ice Truck Killer and the insane Doctor from the last two books.
Lindsay's writing is light and breezy. Maybe too much so as the book goes by very quickly (except for the sections that are not narrated by Dexter; those are tedious and plodding) and the dialogue is fast paced and cinematic. I almost wonder if Lindsay wrote this book with the third TV season of Dexter in mind.
In terms of the series, this has been my least favorite Dexter book so far but I am still interested enough that I would read a 4th one should Lindsay write it. But, if that one also disappointed, I would seriously consider not bothering with any more in the series.
On a scale of 1-10 (one being lowest, ten being highest), DEXTER IN THE DARK rates a 6.5 It wasn't great but it wasn't the worst thing I've read.