Pros:

Wonderful level design/locations

Tricky navigations and mazes make it more fun, not annoying

Solid layout with no glitches

Amazing atmosphere

Fog was very cool

Cons:

Too many Special Infected spawns

A few weird panic events

Lack of dialog/npc interaction. 

Midnight Riders?  Ew.

Conclusion:

The fog was so atmospheric, I kept thinking of how cool it was, and how much it reminded me of a good film.  The only downside was the ridiculous amount of jockeys and smokers that kept spawning.  I get annoyed when people complain about navigation troubles.  To me, if you get lost, it makes it more fun and challenging.

I also would have liked to have had more interaction with the AI's or connection.  The finale didn't make much sense to me, and I hate the midnight riders.

Weird panic events such as the old door were silly.  I do enjoy the startling of the crows, however.

Overall, this campaign is very solid, and is well made.  It lacks a few things that keep it from being really standout, but it's still a great ride.

8.6/10

Pros:

Lives up to its word of 'challenging'

Some very unique mechanics

Some clever events

Cons:

Quite sloppy

Quite glitchy

Obscene amounts of hordes just get tedious wave after wave

Music very irritating 

Conclusion:

I can appreciate what the intended purpose of this campaign is, but for me it was not a fun ride at all.  I felt like I was playing a campaign with glitches galore and very unrealistic premises.  I much prefer 'traditional' maps, in terms of realistic scenarios and events.  

I admit, the first part of the campaign was interesting, and it caught my eye...but after stage two, things went completely downhill for me.  Safe rooms being wide open with infected coming in, AI's going through walls and getting killed with out being able to be saved.  Just very unclean.

I don't like giving negative reviews, and like I said, I understand that this campaign is more of a fun challenge rather than a 'gorgeous achievement', but I still did not like it.

6.0/10

Pros:

Wonderful visuals and layout

Fairly paced

Great variety of locations for general area

Good events

Cons:

Helicopter can see one small flare in a brightly lit window ledge and know there are survivors calling for help?

Prefer L4D2 survivors 

Conclusion:

I feel like this campaign is as professionally made as possible.  Wonderful visuals and layouts....very realistic.  I could go on and on about how well made this campaign is, but I will save space by saying this: superb.

However, as smooth as it ran and perfect as it may seem, it didn't stand out in terms of locations or events.  Just didn't astound me.  But like I've said in other reviews, glitch free and well made > cool locations and events. 

9.5/10

Pros:

Stunning visuals and layout

Incredibly good AI and NPC dialog

Incredible NPC interaction

Very fun events

Very clever idea for campaign

Great finale execution

Fast paced

New ambulance stage very creative

Depletion of health from toxin much more balanced

Improved AI behavior

Length increased

Cons:

Still dislike different starts for the team in initiation

Conclusion:

This improved version is absolutely fantastic.  All of the flaws from the first edition have been fixed, and new additions just make this campaign marvelous.  It's like a totally different game in terms of missions and interaction.  Great great job!  Near perfect in my standards.

9.8/10

Pros:

Unbelievably amazing design

Very realistic

Made me think  "this would make a great film scenario"

Good sound effects

Funny dialog between Nick and 3 L4D surviros

Cons:

The well was ridiculous

Way too many stairs in stage 2

Stairs/elevator led to random place

First two stages seemed rushed

L4D1 survivors make no sense

Bizarre locations/places in the area.

Conclusion:

Wonderful layout.  Wonderful.  Absolutely loved the desert like areas, and ADORED the rural/highway areas.  Very very well made and incredibly realistic.  But I had a hard time with having weird locations like caves or the medieval church...seemed out of place...a lot.  

However, some of the events, like the well, were really unnecessary.  Ellis wouldn't go down (twice!) and I had to wait until a special infected killed him.  Sometimes breaking through doors and barriers got a little tedious.  I like them, but not over and over.

Sound effects were great, and I really liked the eerie music I noticed in the house.  Made it almost kinda creepy.  Really laughed when I heard Nick ask the L4D1 characters if they wanted to join, and how he'd be willing to leave Ellis behind.  But...it made no sense why they were there.

Overall, a very beautiful campaign that sometimes struggled to make sense.  The positives outweigh the negatives, however.  

8.8/10

Pros:

Great detail to environment

Good transition of time, weather, and location

Good sound effects to respecting surroundings

Item placement

Appropriate dialog

Cons:

Sometimes felt sloppy or rushed

Some poor events

Often laggy due to size of maps? (For my experience)

Conclusion:

My initial impression of this campaign was fairly negative.  It seemed clumsily put together in the first map.  The second map was better in terms of detail of layout, but it seemed overly bizarre and unrealistic for an actual place.  Regardless, it eventually got prettier and smoother overtime, making it a solid addon.

The biggest issue I had with this campaign was the frequent decrease in fps.  Perhaps it is my device, but I haven't had this issue with the many other addons I've played.  It was persistent enough to take away from the enjoyment aspect.  

The alarm event was a complete bust for my experience.  Maybe I'm just stupid, but I didn't have a clue what the "get back here, gate is down" meant, and was stuck for about 5 minutes.

Overall, this campaign didn't amaze me, but that doesn't mean it's not good.  It is very professionally made with no glitches or errors, and that makes it easy to recommend.

8.4/10

Pros:

Breathtaking visuals and layouts

No errors or glitches

Decent events

Unique area

Cons:

Seems similar throughout 

Tedious ladder climbing

Harsh lack of dialog

Conclusion:

Despite the fact that this campaign suffers from lack of character interaction and dialog and location variation, it is a very well made addon that is smooth and well executed throughout.

The visuals and designs are simply gorgeous.  When I played it, there were no hiccups--just well detailed structures that were extremely pleasing to the eye.  

I've never played half life, so perhaps that is why I felt I was pretty much playing the same map over and over.  Stage 2's (If I remember correctly) had an annoying amount of ladder climbing to get to the next part in the map.  It wasn't annoying enough to subtract from the quality, but it was boring after like 8 ladders.  

The events in this addon were neither amazing or lame.  They were average events that worked well with the campaign's layout.

Overall, this above average campaign's visuals are by far its greatest pluses.  It's professional feel will make it easily recommendable.

9.1/10

Pros:

Great city campaign

Nice visuals--no glitches or errors

Professional layout

Cons:

Generic feel

Occasional ugly textures

Conclusion:

Although this campaign suffers from pretty much nothing in terms of technical issues or uneven gameplay, I felt like I was playing a generic been-there-done-that package.  Regardless, the city feel was as authentic as possible, and it certainly kept me going.

The maps were nicely laid out and flowed well.  Good events and fair final.  There were some bizarre textures that seemed unnecessary.  

Overall, this seems more like a Crash Course bummer rather than a Dark Carnival innovation, but it's solid in itself, and should not be missed.

8.5/10

Pros:

Wonderful variety of locations

Gorgeous layouts and visuals

Good length

Good pacing

Very fun finale

Cons:

Lag during high tension parts and panic events

Easy to get hopelessly lost in some areas

Too many alarmed cars with auto-triggering

Conclusion:

Certainly one of the best campaigns I've played so far, and a very pretty one for that.  Starting out in the countryside after a plane crash, going through suburban areas to make it to the urban downtown only to end in an overrun military base includes a very hearty feel for all types of location.  Graveyards, cornfields, highways, woods, riverside, capitol buildings, apartments, downtown streets...everything!  That alone was one of the biggest pluses for this campaign.  Closely behind was the design of the layout and visuals.  Generally, very pleasing to the eye with only a very small amount of strange textures that seem to be overly done.  From what I saw, no glitches or errors.

I found myself being kept satisfied throughout the entire campaign, not being to distracted by any length issues.  However, on more than one occasion, I tended to get lost due to lack of clarity and direction markers.  I seriously managed to get stuck at that apartment complex or hotel for ten minutes wondering where I needed to go.  Finally I backtracked and somehow made it to the next area without even knowing it.  Same thing happened (for much less time, however) in the parking ramps...where the car alarms seemed to activate by themselves, which was bizarre.  

I also noticed that the game lagged at times during high pressure situations.  It didn't distract me too much from the game, but it would have been better without.

Overall, this is a wonderful campaign that manages to cover a lot of material and experiences.  It certainly should not be missed.

9.4/10

Pros:

Clever and interesting ideas for events

Good scenario design/layout

Clever 'safe rooms'

Occasional beautiful visuals and layouts

Cons:

Strange infected behavior

Bizarre hordes that occur far too often

Occasional visual glitches

Events/tasks often make no sense or are not clear enough

L4D1 character cameos make no sense

Character dialog often makes no sense

Obscene amount of tanks in finale

Conclusion:

This campaign struggles mostly with the curious AI Director, which behaves strangely throughout entire ride, often spawning hordes in the most out of place times and places ultimately making this an overly difficult campaign.  It's harshly applied during the finale, where I recall seeing 5 tanks come at us.  

The tasks/events in this campaign tend to be equally intriguing as they are rather irritating and confusing.  Generally they are clever enough, but a few suffer from clarity and even logic.  Often times it seems as though they don't work properly until after several tries, or you just have to wait a long time after initiating one for it to work.  

I had a hard time with characters in this one.  Majority of the time, the survivors will blurt out completely irrelevant statements that ruin the mood...and the L4D1 survivors make an exciting appearance, but then end up being of no significance.  What a waste.  

The layout of scenarios was my favorite part of this campaign.  Nice designs, and mostly non-linear.  Visual glitches did hurt their quality, though, and that was disappointing.

Overall, this is a campaign that has potential, but harshly lacks many aspects that keep it from standing out as a great addon.  

6.4/10