Has problems.
The game has a really good premise and set-up, but too many problems to really make it good.
To list, here's a few things I would change that I think would make your game great.
Autoreload: Get rid of it. This is a huge detriment to the game. There's no point in having a back-up weapon if the game reloads for you and forces you to sit through all eight seconds it takes to reload a shotgun. Instead, you should be able to switch to your other weapons when one runs out, and then reload all of them when there's a lull in the attacks.
Weapon Prices: They're unrealistically high compared to the amount of experience you gain per kill. I managed to figure out a way to get some good weapons by buying really judiciously, but the prices of the better guns should be brought down.
Zombie life expectancy: Some of the zombies just take too long to kill. Five shots with a piston I'm okay with. Five shots with an autoshotgun is a bit much. Either take the zombies down a bit, or perhaps give the guns a bit more power.
Saving function: It's a nice idea, but it doesn't work right. The numbers saved works, I came back in with the right experience and level, but I only kept the gun that I last used when I quit. I lost everything else.
I know it seems like a lot, but I think if you make these changes you'll have a great game.