Left 4 dead 2 is an amazing game, but you may get fustrated at times.
The graphics arn't brilliant, but their not bad. But don't you love it when you shoot a zombie in the stomach for its intestines to fall out!
The single player campaign is good, but dont expect to be finishing it on expert. There are 5 campaigns. There really isn't any point going on single player when you can go online and do the exact same thing.
Versus mode: 4 survivors, 4 infected. Like the campaign, but with human players as the infected.
Survival mode: Try to survive as long as you can. Can get fustrated as a tank comes about every 2 minutes.
Scavenge mode: Try to get as many gas cans in a generator (or car) in a limited amount of time. Really fun game mode.
The bad is the AI. The AI playing as the survivors is so thick. If a jockey is riding on you, it usually takes the AI a few seconds to respond, even if their right next to you. They arn't responsive, if your trying to run back to the safe room from an early tank, the AI might decide to have lunch outside.
Another bad is the difficulty. Easy,normal and advanced are all easy. Expert however, is almost impossible. Sometimes, one hit from a common infected can deal 10 or 20 damage. You better hope a smoker or hunter starts attacking you for more than 7 seconds, otherwise, your dead.
Overall, left 4 dead 2 is must.