Man, when they said mad horde, they weren't kidding. I was like O_O, and it was the first level. Know that alarm from Dead Center, in the mall? It was a crescendo like that (short level) that never ended. When you first leave the area, there's at least 5 incoming attack notifications. xD

But, anyway, it's a really great campaign. It combines a lot of the aspects of Dead Center, No Mercy, and Dead Air. The higherups really. The challenges never end either, with the craziest witch spawns I've seen since Death Toll 3. And if you're big on fighting tanks, this addon campaign is definitely for you. Before you get to the finale, you will encounter at least 5 tanks. And it's not as easy as you might think.

Highly recommend this one. Check it out L4dmaps.com. Play on EXPERT. It's sexy.