It's unfortunate that Ubisoft decided to end with something so weak. The first two DLC were fantastic fun, but Dead Living Zombies fails to be innovative, with a very light coating on top of a glorified Zombie Mode. I honestly don't know how they could have made this better, but I'm sure it was possible. A lackluster end to the season pass trilogy, and to my time with Far Cry 5.
A real eye-opening experience, for someone not well versed in the Vietnam War outside of Forrest Gump, it's a welcome change to the main game, and that's coming from someone who really enjoyed the main game! If you're looking to creep around a jungle blowing things up and snapping necks, then come to Vietnam. If you weren't a fan of the main game, this probably won't change your mind.
It manages to improve upon the previous game, and thankfully fixes some of it's problems. Since you can import your save from the last game, you should probably check that out first - it will help give you a deeper understanding of the story too.