Pros:

- A Portal Like feel to it
- Use gas cans for weapons and such
- Puzzles that require you to memorize
- An environment that is set to "Surprise" you
- Awesome laser hall way
- Awesome "scanner" to make you on fire
- One of the most adrenaline filled finale escape ever
- One campaign the survivors will never survive or escape

Cons:

- A single charger and tank hit on some high areas can pretty much destroy the entire team in versus mode. This can cause survivor players to rage quit as it's favored more on the infected side rather than on the survivors
- I had no idea you had to melee the paintings. Since there highlighted, your first instinct  is to "use" them. Once I figured that didn't work. I suspected that you would need to "use" them in a different manner. It wasn't until much later that I figured out you had to melee them. A little more of a clue could have helped out more
- The "spawn holes" makes it obvious where the infected can pop up at. In a well balanced group it can be easy to predict how the infected will come at you, IMO giving you a slight advantage because you know where they are going to spawn at
- Since it kinda has that portal feel to it. Having GLaDOS there would've been awesome

Conclusion:

I really like the idea where you would need gas cans to get some items and you could only choose between one of them. This tells the player that the gas cans are a valuable part to the entire campaign. The puzzles are introduced in a manner where you wouldn't get confused or lost on what to do. Then there re-introduced in different manners and intensify as you progress further into the campaign. The car dropping shaft, laser hallway and spinning room, are just some of the things that makes this campaign well worth playing. The finale gives you a rush that you never felt before, with the infected barreling you down and more of the puzzle returning back to back. Rushing to the exit, water slowing you down cars falling from the ceiling then when you think it's all over, BAM! Another keypad to enter. As you make the final sprint to the end, where yo see the world at the end of the tunnel. You get the biggest surprise ever, with IMO, the best ending ever in a custom Left 4 Dead campaign...

Pros:

-Nicely detailed maps
-Sorta feels like Resident Evil with all the twist ant turns you gotta make
-A lot to do, almost feels like your playing twice of the average campaign 
-Playing as infected is far better than the Survivors. 
-Lots of high areas for Smokers, Jockeys, Spitters and Hunters

Cons:

-With all the twist you wonder when will the map end. Because of this it can get a tad boring / tedious
-Too much to do, too much running around
-Horde comes in way too often with very little time to rest
-Because of the length, the campaign is hard and test your endurance  

Conclusion:

Not surprised it's another city layout (Not like we have enough of those but doesn't matter). Without all the twist you'll have to make, the boring-ness would've came in much later. But I was bored by the 1st map. This is one big endurance campaign. If you get past that fact, you can have some fun here. Versus mode is where it shines more but that just mean the campaign is even more harder.

Pros:

-Really well made maps
-An oil refinery, never expected that
-The creepy atmosphere while in the ship made the infected seem freighting
-Barrel room is just a reminder not to misfire the infected
-Finale was difficult in a "Hurry with the gas cans" kinda way. But was fun
-Just All Round Fun

Cons:

-Underwater area was kinda of a nightmare with the bots always healing near death then get incapacitated
-Finale was difficult in a "Where's the healing items" kinda way

Conclusion:

This was a very challenging campaign, with traps, a creepy environment and a hard as heck finale. This one deserves the "Expert This !" stamp. I can not image the difficulty with the bots on Expert. It was kinda hard enough on Normal...