Pros:

Very Different
Nicely done
The "Do Not Enter Room"
Difficult Ending

Cons:

None Really For Me.

Conclusion:

Loved it! Amazingly done. I hope a lot more people play this!

Pros:

-Graphics are amazing
-Tank skins are cool
-Sound tracks/custom sounds are very original 
-Trevor the dog was a very nice touch
-A lot of room and wide open space to explore 
-The setting in all maps were very impressive to me 
-Voices and the TV thing was very cool in my opinion
-Maps were long and kept interest at the same time which is very rare
-Custom textures
ECT ECT

Cons:

None that I found :)

Conclusion:

Great campaign! Very nice work and I simply love it. I could play this campaign over and over again and just not get tired of it. Keep up the good work!

Pros:

Fun
The Jukebox sounds with the 1st L4D Survivors 
The survivor sayings throughout the campaign 
Difficult 

Cons:

Gotta carry around a grenade launcher...

Conclusion:

Way more difficult than the first Questionable Ethics and i liked that. Its a great campaign!

Pros:

Fairly Easy (I played with bots)
Fun Tests
The "All I Want For Christmas" Song Plays :)
An AWESOME Ending
The Survivors Have Cool Sayings In This 
Cool Large Areas 

Cons:

None For Me

Conclusion:

I had an amazing time playing this and I was playing single player. 

Pros:

Link as gnome
Cool Melee weapons (Mmmm dat knife)
Awesome beginning
Hard  Maps
All the fire
Puzzles 
Boulders 

Cons:

Bots are terrible in this campaign!!

Conclusion:

Just amazing!!!!!! Definitely the overall best campaign I have ever played, but if playing with bots can get very irritating