Pros:

Everything. Literally everything from first saferoom to epic finale. It's not short, not too long.
Perfect.

Cons:

I fail to find any con, sorry.

Conclusion:

This is the best campaign of this year.

Pros:

Total reskin and resounding of everything and everyone really suit's camapign's atmosphere which is there, that'd work way worse with original l4d2's cartoonish style.
Whole level retexturing right when playing? Briliant. However I'd say it changes too frequently.

Cons:

Map 5 was plain boring when fallowing the endless road.
Many of interactive items that were supposed to tell story showed nothing or ERROR.
I AM ERROR

Conclusion:

I doubt Valve will ever you whole l4d potential even in l4d3 especially now with focus on versus. If you ever wanted horror coop game that is actually horror than here it is.

Pros:

This one is... Exceptinal. You can see that either mapper wasn't very good either did not try much, however it's definitly fun to play.
Map 2 is still my favourite.

Cons:

I remember finale of this maps being something like alien space ships with giant transparent structures in large darkness. What happended to it? Why finale now is sucj an awful map? I'd prefer eternal darkness with transparent structure to this "my first map" even if it was a glitch.
Also there are errors on map 2 and 3.

Conclusion:

I remember guy felt sick on map 2 long time ag in l4d1, now I can make sick a lot of people again, but fun kind of sick.
This campaing really needed to be ported.

Pros:

I find dark claustraphobic environtment to be more of a pro than con since there are too much "muh open space" campaigns already and we still were able to fight tanks properly. No event abuse.
It was fun, that's all want you may want from a game. Had good laughs.

Almost forgot, why is there so little "THE PARISH" style finale? they are way more interesting than camping.

Cons:

Levels are too long, I mean there are only two of them and one finale, but I'd rather had 3 or even 4 maps instead to aoid died-near-saferoom-at-terribly-long-level frustraitions. But it wasn't too hard, although I'd put more respawn points on level 2.

Conclusion:

It's a great campaign and don't believe anyone who says otherwise.

Pros:

Very fun camapign with simple yet interesting design, it looks in first person way better than on screenshot.

Cons:

Short.

Conclusion:

Fun, but short.

Pros:

Very good maps with references to such horror films like Evil Dead, Lord of the Rings and Harry Potter.
Complex architecture, it's very interesting just to wonder these maps. Great idea.

Cons:

That which is supposed to be Iniana Jones map (I suppose) looks kinda weaker than the others.

Conclusion:

I must say I use this campaign a lot to lure people into playing custom maps.

Pros:

I must say I really liked the environment, maps are not really large, but feel big for some reason.

Cons:

Well, it's short.

Conclusion:

I must say short campaign is much better then when quthor tries to artificially prolong it or puts a lot of boring stuff in.

Pros:

Nothing special or good.

Cons:

Nothing too bad either.

Conclusion:

Nothing to even conclude. Just a long obstacle race with zombies, someone maybe would've even liked it, but l4d is almost five years old, so I doubt it.

Pros:

This is the most detailed campaign for l4d in existance, everyone should play it, I could not believe my eyes, it was worth waiting.
Versus was good too.

Cons:

Detail level is so high and maps are so huge that you may experience major lag.

Conclusion:

In Soviet Russia zombies are hunted by you.

Pros:

Lol lol lol lolol lol lol. Lol lol lol lolol lol lol. Lol lol lol lolol lol lol. Loooooooooool. Loooooooooooool. Looooooooooooooooooooooooooool.
And than you die.

Cons:

Lol lol lol lolol lol lol. Lol lol lol lolol lol lol. Lol lol lol lolol lol lol. Loooooooooool. Loooooooooooool. Looooooooooooooooooooooooooool.
And than you die in front of safehouse and rage.  I wish especially deadly traps would be only in the bbeginning of level. I also wish for spawn points.

Conclusion:

LOL
No words, just see it.

Pros:

Vast open spaces

Cons:

Complete lack of design, maps are simple and narrow and consist of piles of objects.

Conclusion:

Just editing score because campaign indeed became better and even playable after update.

Pros:

Good devercity of mpas, lots of custom models, interesting locations.
Levels are really long and exteriorrs sometimes seem very detailed.

Cons:

IInteriors on the other hand are bland, sometimes to much of copy/paste.
We spent to much time figuring out how to get out of starting point on map 1, but I guess it's because of lack of localizotions.
Missiing textures are common, but it's fine.

Conclusion:

Good campaign, you never know what's waiting for you behind the next corner, I belive I'd liked it even more if I undertoon anything.

Pros:

Very impressive scenery and fast-pacing gamepley, also level design leads to very interesting situations, funny traps.
Not easy campaign, but not too hard.

Cons:

Most levels are really highly-decorated halls.

Conclusion:

Fun to play, despite lower rating, this is second best camapaign from Chinese contest.

Pros:

Awesome scripts, music, very fun gameplay.
Very detailed environment and interesting map design not similar to "traditional" l4d.

Cons:

Scripted movies during gameplay. While they are playing zombies still beat you, I'd rather have all that scripts but remain in control of my character.

Conclusion:

Big non-linear maps, hard gameplay, interesting environment, lots of stuff to entertain in this three-years-old game.

Pros:

A port with incredible Silent Hill sounds and music.

Cons:

At map 7 fog should have ben transformed into darkness after fake safehouse.
No melee weapons added.
Pushing buttons in 6 4 8 puzzle drove me nuts because when I pushed one I aslo pushed another on other side.

Conclusion:

L4d2 port of the longest and the scariest l4d1 campaign.
I with there were more horrors.

Also, some poeple have troubles fining sound folder.

Pros:

Very fun to play with friends.

Cons:

None, really.

Conclusion:

Do you know this campaign gets so many positive reviews? It's becuase author instead of strangling own creativily by choosing one of generic zombie settings got inspiration most likely from portal and put a traps and challenges not common for 3D first person games.

No hope for creativity from big game industry, but at least we can have it here.

Pros:

Has some non-linear paths, detailed design.

Original surcivors for those who don't like new ones. I suppose nobody really prefers new survivors over old ones.

Cons:

Very, I mean VERY long and boring third map. 
Finale is very mediocre, maybe even worse than Valve's.
Valve style. Valve style is everywhere.

Conclusion:

Because of boredom we couldn't complete it neither in l4d1 or l4d2, however it was fun in versus.
Finale scoring is broken by the way.

Overall rating shows that advertising means much more than quality.

Pros:

l4d1

Cons:

l4d2

Conclusion:

This was one of the first campaign released for l4d1 back then and I must say definately one of the best which are superior even to official ones (I mean in l4d1. In l4d2 official capaigns are crap anyway). 
Works perfectly in l4d2, the only difference is daylight which is con for someone.

Pros:

A lot of dark areas which l4d should be about. second maps have interesting chase sequence.
I also like that many weapons can be taken only once.

Cons:

First map is short and easy.
4th map is just horrible and annoying in all ways. 

Conclusion:

Not that bad. If finale wouldn't be so horrible I might have even played versus on it.

Pros:

One of the little maps which use weather effecs.
First two levels have awesome atmosphere.

Cons:

Third level does not  feel very good compared to first two.

Conclusion:

This campaign took a lot fromt official Hard Rain and Swamp Fever and made it even better.

Pros:

MARIO TIME! I've found it quite interesting  Environment is cool. Level design is great.

Cons:

No details, but it's 8 bit style. And it's easy.

Conclusion:

Will do for those who are thick of urban maps.

Pros:

1. Silent Hill atmosphere.
2 .Many original ideas.
3. Maps fit l4d perfectly.

Cons:

1. If you are not SH fan or at least haven't played SH1, you'll gonna have problems.
2. I've suggested in comments to make two campaigns. It's very long indeed, but this is not something that can ruin awesomeness.

Conclusion:

This is my favourive campaign for l4d.