May be my favorite game of all time.
I'm only 5 days in but I am super hooked. Why? The War Z is very different from any other game you've been playing. It has guns and a FPS interface but it's not a shooter. It's a survival game.
When you spawn in you should assume everything is going to try and kill you. You have to really feel out a player before you team up and you never have enough gear. Why, because it's about survival. Can you do more with less?
If you want to have the best gun or flashiest armor then you'll hate this game. If you need a quest giver to tell you what to do you'll fell lost. But if you just want to figure out if you can live in a hostile world with a flashlight? You've found your game.
I just did a "naked" raid of Boulder City and it was crazy fun. I went in with an empty backpack and had to sneak everywhere I went. I had a zombie chase me through 2 buildings before I found something to kill him with. After that I managed to cross the width of the town solely with loot I found on that run. It was a rush.
The game does have the feel of a beta. I will give the haters that. There isn't much other than the vault in safe zones. The sounds are still quirky and there is the occasional aimbotter.
So if you're looking for a crazy, dangerous, free zombie world this game is for you. I'm hoping they continue to polish it and you'll read this and join. Good luck!