Pros:

Still amazing, still unique, still just the best there is when it comes to custom content. (+5)
Decorated and designed. even for an underground facility (+1)
Fun as fun gets (+3)
Ordnance delivered fairly (+1)

Cons:

Forces you to have a Grenade Launcher on your person at all times (-0.2)

Conclusion:

As good as the last one, if not better. A definite download for anybody looking for custom content. One question - will this be a trilogy? And if so, where's the 3rd?

Pros:

Original, interesting, intelligent... pretty much every positive adjective describes this (+5)
Unique finale... scratch that, unique everything (+3)
Extremely fun (+2)
Ordnance is given in good amounts that aren't overwhelming nor invisible (+0.5)

Cons:

Specific infected spawns (kind of takes some of the fun out when you know where the tank will be everytime) (-0.5)
Not built for AI teammates (-0.5)
Bland decor (this one is mostly preference, considering you would expect a dull background in a research facility)

Conclusion:

One of the coolest custom campaigns to ever touch Left 4 Dead 2. Worthy of a download, without a doubt. Extremely fun, challenging, and unique describe it perfectly.