I totally agree. Some people complained about the game being too short in length, but personally I don't see that aspect being a downfall by any means. The content which the game delivers is quality and action packed. For me, there is nothing worse than when a game becomesso long and drawn out to the point where it feels like I'm just trying to grind through rest to reach the end. In short, the L4D story is intriguing and concise for what it is, and most importantly delivers a fun gaming experience.
On a side note, I enjoy that the gameplay is broken up into campaigns, and then is even further disected into chapters. It is a feature that allows the 'hardcore' gamer the ability to go back and play specific segments that they would like to practice or rehearse on different difficulty settings, while at the same time allows for casual players to resume where they left off at their leisure
Though I am only half way through the game, thus far I am having a blast. I can't wait to begin the third campaign!