Worth the wait? Absolutely.

I've been tracking this one since it's concept was mentioned years ago.  When I finally got my hands on the demo, I logged 30 hours easily just on an incomplete stage.

The game was inspired by the developers playing Counter Strike and pitting themselves against massive amounts of bots with knives attacking a few of them with guns.  This translates well to what Left 4 Dead became.

On the surface, Left 4 Dead is a Cooperative First Person Shooter in which players will survive hordes of Zombies while trying to get from point A to point B.  On the inside however, it is very solid, cut and dry dynamic game that encourages teamwork and creates some interesting situational random moments.

The game features a "Director" which monitors your playstyle, stress levels, and advancement through the environment.  It creates its own peaks and valleys of excitement as you play through a stage.  One moment your swarmed with livid zombies, and the next, you're listening to the ambience of an empty level wondering what is going to happen next.  This feature is the pure genious of the game.  Random zombie spawns is the winner here.

There are also randomly spawned "Boss" zombies which add greatly to game play depth.  Their individual mechanics are solid and force team work behavior amongst the survivors.  You'll hear them coming, and will have to plan accordingly so no one gets singled out.  They add great gameplay depth, and there's only 6 of them.  There's a heightened sense of danger everytime you realize one is in the area.

The storyline is very shallow but just consider it a benefactor to how replayable the game is.  The basic premise of the game is to survive.  Cutscenes and long dialogue don't belong here.  The game is built for replayability and anyone a fan of first person shooters gets the ADD itch to keep moving.  There's four campaigns which will roughly take an hour to complete with a B grade team.

L4D would've gotten a 10 from me if the graphics weren't a little dated on the Source engine, and the characters you play didn't feel like super troopers in regards to speed and melee power.  The weapons are also simple.  This is just my taste however, after playing dozens of FPS and having many variations of a rifle, shot gun, or sniper rifle.  I feel the selection falls a bit short.

This is one of the most solid and innovative games to grace gamers in a while.  There's plenty of difficulty modes so everyone can try it, and love it.  I'm sure you'll be telling stories after a few run throughs.  It's very rare you'll step away from this game after surviving a campaign and not feel like your experience was short of friggin awesome.