These are just some of my first impressions, I'll edit as I play with it a bit more.
When I started playing I was amazed at the number of zombies that were roaming around. You start of on the ground floor of a mall surrounded by literally hundreds of undead monsters, if not a thousand, which all stand around confusedly some of them still trying to do normal things like push around shopping carts (which created a similar atmosphere to that of the original Dawn of the Dead). The number of zombies on screen didn't have any affect on the framerate at all either, and all of the animations were extremely smooth however they are quite repetitive. I doubt that will be much of an issue though, there's an unbelievable amount of things which can be used as weapons, you can pretty much pick up anything at all. The most impressive I found is the shopping cart, which you can drive around like a battering ram and mow down dozens of zombies. Completely awesome.
So back to the gameplay, I started hacking away at the hordes of zombies, killing 150+ before I started exploring. It was just as fun killing the last one as it was killing the first. (so hopefully it won't start to feel like a chore killing so many zombies, that's something I was worried about). Like I said before there's an astounding amount of things which can be picked up and used as weapons, I spent ages just looting shops and testing out the different weapons and then began to change my clothes, when I got ambushed from behind and was completely
I've gone on for way longer than I wanted to, but yeah, this game is amazing. The graphics, animation, controls and gameplay are all great, you definetely need to play this game.