Well a friend of mine graciously bought me a copy of Left 4 Dead in celebration of a job he landed. I think it was also because he wanted to be sure he had a buddy to play with :P
So, how does the full game compare to the demo? Let me just say the demo really did not prepare for the insanity that would ensue in the full version! This is quite possibly the funnest multi-player game I have ever played! Most likely this is due to the fact that Left 4 Dead was developed as a multi-player game first and a single player second. Most games are developed with that philosophy in reverse. Which is why many times multi-player can feel tacked on, like an after thought. In Left 4 Dead it feels as if the single player exists primarily to practice for the multi-play. Since Left 4 Dead is based on the Source engine, it will be interesting to see what the modding community creates.