Oddly enough, I didn't pick up this series first. I picked up Angel Lawson's book FanGirl. It was a cute romance about a girl obsessed with a zombie comic book getting to meet the comic book's author and their falling in love. Angel published the romance in 2012, with lots of little scenes from the zombie comic book interspersed in the story. Then the fans must have cried out. Because in 2016, Angel published The Girl Who Shot First. It IS the zombie comic book story, in novel form. I thoroughly enjoyed FanGirl, and give it a 5/5 stars. It doesn't matter whether or not you read FanGirl with the Death Fields series. But any "spoilers" in FanGirl all appear in the first book, so don't worry about knowing too much about later books.
Although I am not typically a zombie fan, I did enjoy The Girl Who Shot First. I enjoyed the plot (which I had roughly known from reading FanGirl) and the descriptions and the characters. I was thoroughly satisfied when I got to the end of the book, but I debated picking up the others. I really, really enjoyed The Girl Who Shot First. But I was ambivalent about continuing the series. This rarely happens with me, but to be fair, it usually happens in a genre I don't read often, like zombie apocalypse.
While I can heartily recommend The Girl Who Shot First, I cannot tell you about any of the other books in the series. I thought, "Well, I'll go read something else, and if my curiosity kills me, I'll come back to this series." It never killed me, so I never went back. Like I said, I was thoroughly satisfied at the end of The Girl Who Shot First. However, if you really love zombie apocalypse books, you'll most likely enjoy the entire series because the first one really was very good. 5/5 stars for The Girl Who Shot First.