the book is very good but when I read it I didn't fully understand a lot of the stuff on a broader context. I'll enjoy it much more on a re-reading.
the series never followed a storyline from the book per se. on the other hands little parts from the book are always here and there. even on the 4th season they're still pulling stuff from the book like the story about the wastelands in southern Italy being used as an illegal deposit of toxic waste and cadavers. the author tells of a certain region in Campania where there are constant explosions coming from underground for no apparent reason which happens because of the toxic waste that's buried there.