Which is an odd choice to kick start the series. Because "Savage Season" was originally not part of the Hap and Leonard book series, it was a stand alone novel with the characters appearing first time ever. What would become known as the "Hap and Leonard Book Series" started with the intense mystery, amateur sleuth books like "Mucho Mojo" and "The Two Bear Mambo", and the rest is history. While the book series has ups and lows as any series, I never got tired of reading all of them.
The TV series is almost I would say dedicated to new and old fans of the books, the casting and the details are all there, so while Joe Lansadale's prose is gone it is a hell of a treat for readers that can approach an on-the-screen version. I am unable to tell how this TV series will sit to newcomers, because the plot ruminates deeply on themes that prevailed in Savage Season (i.e. the idealism of the 60s, and its reverberations into the late 80s) but were lately abandoned in the books which became their own distinct brand of crime mystery novels. And that is unfair as I am leaving out a lot of themes in the novels, really.
So give it a try, and if it lets you down just wait until the second arc comes out. If they adapt Mucho Mojo as it is hinted... or The Two Bear Mambo, or any other book with Hap and Leonard the plot will be much more intense and focused than this one, and the potential to rival with other mystery TV series like "True Detective".