I started playing this in Co-op with a friend not long ago.
So far it has been really fun and holds up great. The world is really fun to explore and the parkour movement is some of the best of recent times. After getting used to how everything works, moving around is fast and intuitive and unlike so many other games where parkour is basically engaged with a button and you almost move automatically (like Assassins Creed), here your input is still very important. Also, at least early on, the game does a great job of making you feel vulnerable but still capable. You are almost inhumanely good at parkour and moving around.... but big groups of zombies are still a scary sight you have to avoid and going out at night (when stronger enemies come out) is always incredibly tense and rewarding
The only thing I haven't liked is combat with other human enemies (zombies, on the other hand, are fun). I expected them to be intense encounters where they can kill you really fast but so do you (because they are human so a stab to the face should be lethal). Instead they are damage sponges and it all just feels a bit clunky and janky.
Don't know if there are paid DLC (aside from the expansion). But if there are the game is definitely not very "in your face" about it