Far too many issues, bugs, and glitches.
All of them fixed in The Last Stand 2.
Only way to beat this game is to slow the frame-rate so the zombies move at a much slower pace. If you have a new computer, forget it. Zombies move too fast, your initial weapon might as well be a BB gun because it barely stops them, even when you aim at their heads. Speaking of aiming, it doesn't matter because sometimes your bullets just fly right through the zombies as if they aren't there. Even when you stand directly in front of them and intentionally aim at their heads. If you do find survivors, they are pathetic shots armed with pathetic guns early on in the game. Making them useless.
All combined, it makes the game unplayable past a handful of days at most. One bug is that sometimes when you die and hit "retry," you get a gun that doesn't fire at all. Don't waste your time with this one. Play The Last Stand 2 instead. It's a much better game.