I bought this game a while ago and was playing through it then I got pulled away by other games. A friend of mine got it out of the blue so I went back to playing it so I could play with him. Needless to say I've been playing mostly this and last night I finished the game for the 1000 points. I'm not buying the DLC to finish it completely so I'm done with the game.
When I first started playing the game, it was really hard. Everything you do, you take at a slow pace. I mean, why wouldn't you, there are zombies showing up everywhere you go. Actually completeing the game for first time through is going to take you a while to do. There is an achievement in the game where you have to finish Act 1 with all 4 players. Which is the last achievement I got. After replaying that Act 1 for four times now. I've gotten pretty good at this game. It doesn't take that long to get through the quests that are given to you. I even run more and take out the zombies easier. Mobs are still hard as you just have too many to swing at and can't get them all. Even so, this game at a fast pace is still fun to run through.
Part of the fun this game has is you get to mod weapons. You have to find the blue prints in order to be able to make them. They are scattered around the entire island, so you need to look for them everywhere you go. Upgrading them changes the look as well so don't just leave them at level 1. Max out the level of the weapon. One you will really see change is the Hot Rod mod where your big knife will turn an orange glow like it's on fire. It does some pretty good damage.
The game does have some glitches but I'm not going to linger on it. I just wanted to mention to have a 2nd save of your save file as when you connect to someone or they connect to you online, if it freezes up, there is a possiblity that you could lose all your inventory for your character or lose that save file comletely. So be careful when you start playing online to get your achievements or even with your friends.
There are a few guns in the game that you can make or get from someone who has them that are glitched guns. I have an assault rifle that never runs out of ammo and kills everything in 1 or 2 shots. I have shotgun that has lightning bullets that come out and destroys anything it hits. I also have an unlimited sniper rifle. So if you want to make the game easy, get your character to level 20 and you'll be able to hold these guns if someone gives them to you.
If you're looking for a good zombie game to play and you like open world, I would recommend picking up this game. You will definitely enjoy it the more you play it.