Pros:

The five level thing was fine.

Cons:

Nothing else was.
Fog.
Bland.

Conclusion:

The fog was useless, the train ride was long, and the bots had no idea what they were doing.

And what the hell was wrong with Bill?

Pros:

looooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooong
long
good for hunting rifles and smgs
and cricket bat

Cons:

water
water
water

Conclusion:

pretty neat-o.

Pros:

Everything
Absolutely everything possible possible to be possible possible possible.

Cons:

Nothing
Nothing at all
No Nope Nein Non No Нет Не-а Нет-уж 

Conclusion:

~MOTHER~!@#$ER~

Pros:

Clothes are actually not horrid.
Jewelry fine enough.

Cons:

Again with the eyes.

Conclusion:

Worst screenshots I've ever seen though.
Other than the eyes and freckles, not bad.

Pros:

It's actually not that bad.
Burger King tattoo, though I think it'd be better if it said "Burger Tank"

Cons:

THE EYES!

Conclusion:

It's fine.
I personally won't download just because those eyes will stare into my soul and then remove it and tear it to pieces.

Pros:

Beta Nick.
I like clean suits myself.
No problems with it, everything has been running just fine.

Cons:

Nicht.
Nothing.

Conclusion:

Basically the Nick skin for people who like things clean.

Pros:

New sounds.
Not high pitched
No (obvious) screeches or clicks.

Cons:

Weapons are a little slow.

Conclusion:

Good soundmod.  Worth a try at least.

Pros:

Looks really good, even in low quality.

Cons:

None.

Conclusion:

I don't know what all the problems about downloading were, it worked perfectly fine for me.

Pros:

Killing
More Killing
Killing with Molotovs
Killing with Guns
Killing with more Guns.

Cons:

None

Conclusion:

Killing.  Then do more killing.

Pros:

Good maps.
Not easy.
AI is pretty good, still a few problems with elevators and ladders.
2nd map was THE BEST map for Hunting Rifle; definitely one of the most fun times I've ever had in L4D.
AI was fairly responsive to weapons and ammunition.
(Pro/Con) Minigun at finale was just plain overpowered.

Cons:

The rooftop climbing and plank walking was a deathtrap for bots.
Occasionally difficult to find your way around.
Going through the deep water wasn't fun.
Getting on the traincar in the finale was pretty difficult, Tanks climbed right up next to the chopper, it was hard to get on and not fall off, and it was very frustrating when the tank punched you off as soon as you got on.
Bots have a 0% chance of surviving the finale.

Conclusion:

Fun campaign, good for Assault Rifle or Hunting Rifle users, with plenty of wide open spaces and beam walking.  Definitely worth a download.

Pros:

Fun gameplay.
AI pathfinding is pretty good.
Roofhopping was fun and unique.
Train ride, I've only seen that in one other campaign.
Not difficult, but still not boring.

Cons:

Bots had a little trouble around ladders and on the hole in map 3, but that is expected because bots always have trouble moving vertically, even on stock campaigns. (-0)
Ammo was a little scarce, I used dual pistols quite a bit during maps two and three.  (-.5)
Preview pictures are mostly showing of Zoey mods? (-0)
First level was rather short. (-.5)
Finale was very easy, you were even able to just walk in the saferoom. (-.5)

Conclusion:

A very fun campaign, not long, not too short, pretty easy.  A good campaign for newer players or Advanced/Expert games.

Pros:

Very fun.
Plenty of Dialouge.
Huck died.
The Boomer rigged door was a fun thing to try and avoid.
Miniguns are placed in GOOD places, not like other campaigns where miniguns are pointed opposite of where hordes come from.

Cons:

SMG was pretty overpowered in maps 2 and 3 because of the very thin corridors.
(Maybe Director)  Hunting Rifles didn't spawn until the finale, and even then only in one place.
Map 4 was generally not fun, but that may be because I HATE maps with forests.
A few bot navigation problems.
Weapon spawns overall were pretty odd.

Conclusion:

A fun campaign with plenty of zombies and plenty of heavy turrets to kill them all with.  I got my Red Mist achievement on this level, I killed roughly 250 zombies with the miniguns.  

Pros:

Fairly long.
Plenty of zombies.
Custom music.
Fair amounts of ammo and weaponry.
Fun, fast paced finale.
Combine soldier ragdoll near finale was really good.

Cons:

Nothing comes to mind.

Conclusion:

An amazing rendition of City-17 for Left 4 Dead, very well made with plenty of rooms, corridors, and alleys to explore, and it's based off of a location in Half-Life, so what's not to love? 

Pros:

AI wasn't too bad
Weapons were fine, even though it was easy to get low on ammo sometimes
Long enough
Train was amazing
Not difficult to traverse, most of the time it was a straightforward path.

Cons:

One blue and red flashing light that almost gave me a seizure
Other times it was too dark to see much anything
The river in map four (I believe) was a deathtrap, my entire team died a few times.

Conclusion:

A unique campaign with solid gameplay, if you can get past the lights and river.