
If you like video games like I like video games, then you should buy Left 4 Dead. It is one of the better shooter type games I have played, largely because if you play mulitplayer you have to work as a team. This, in theory, keeps jerks that just like to teamkill and run around like idiots to a minimum. Besides all that, I like shooting zombies.
On the topic of Zombies, I must point out that these zombies lean heavily towards the "28 Days Later" style of Zombie in that they are quite fast. Also, Zombies can effectively be put down by repeated shots to the body. In reality, we all know that Zombies can only be re-killed by head shots, but games are an escape from reality.
The graphics are pretty good, the environment is fairly interactive, and the shooting aspect of the game is easy enough to be enjoyable. I don't want super easy shooting, but I don't want it to be incredibly difficult either. L4D seems to have a pretty good balance.
Buy it, play it, enjoy.