I read this book because I loved the series and I wanted to see how the book differed. As I suspected based on the description, it was much darker! That doesn't mean that I didn't like it, however, and in fact I enjoyed how twisted it turned out to be. The contrast between the simple illustration style and shocking plot twists is jarring (but not in a bad way).
I would warn fans of the show that they probably won't like this book for any of the reasons that they like the show. TEOTFW on Netflix has more of a teen adventure spin on it, and the characters and more sympathetic and cute. While I ended up rooting for James and Alyssa's relationship in the series, I barely felt any sympathy for their book counterparts. The outcome of the book is bleak and there are some dark elements that were cut out of the show. That being said, I like a bit of shock and horror in my reading now and then, so I loved the book in a completely different way than I loved the show!