Once you finish the main story the game just turns into even more of a grind fear than the story is. I would not recommend buying the dlc (as I sadly did) The underground isn't better than any of the main missions but replayed on a higher difficulty. Survival is not for me but I can see how someone would like it and last stand just domination pvp
The dark zone is absolutely trash and I cannot recommend going in without a few friends.
The story is lackluster and as soon as I finish doing all of the missions at least once I'll probably uninstall it's a pretty ok game but definitely pick it up on sale