Pros:

- Nice scenery
- Unique environments
- Interesting ending

Cons:

- Limited ammo cans
- Hardly any melee weapons
- Second pistol only in safe room?
- Dizzying Finale
- Change of atmosphere

Conclusion:

My review is pretty close to that of my fellow critics. It has its good points here and there and its still by far not the worse map I've ever played...but it does need some work. Lack of ammo dumps and melee weapons made it an undesired challenge and the finale had me confused on all the running down then all the way back up? It could have been constructed a little better on that point. But to be fair there are some parts I found rather fun such as the sunken park and safe tent zones with the sneak passage out of the bathroom. Very clever! Its a map that I do recommend people at least try once and form their own opinion.

Pros:

- Challenging
- Nonlinear
- Disable way-finding
- Custom artwork & decals
- Great detail

Cons:

- Loads of dead ends
- Disable way-finding
- Slightly confusing paths

Conclusion:

If you have ever said to yourself: "Gosh I wish I could play a map that had multiple pathways that I could take and also have tons of risks of falling from great heights, that would be swell!" Then Drop Dead Gorges is a map right up your alley!
I proudly give it the seal of approval for most unique map design I have ever had the chance to play, Perhaps not a map for new players but a veteran player will have a blast on this campaign. The amount of custom designs and artwork is a nice bonus too but best not to sit around too long admiring them. It has a challenge in its own regard that makes this a very fun but not too terribly long campaign.
So if you enjoy trying a unique and creative map over all the basic other maps out there...give this a try, you'll not be disappointed!

Pros:

- Good weapon placement
- Atmospheric
- Not too linear
- Simple yet effective
- Dark in all the right areas
- Smooth gameplay
- Crazy ending

Cons:

- Lag spots
- Over abundance of throwables
- Dry opening
- Short (3 maps)
- Boring layout (Factory/facility)
- Crazy ending

Conclusion:

The pros outweigh the cons on this map by a small margin. It was still a fun campaign to play and I recommend people at least give it a try but it did have some issues here and there. 
The opening seemed overly simple and could have at least used a scenic driving shot down a hallway instead of just going straight to character. As some other reviewers pointed out the excessive amount of Molotovs and pipebombs made the ending really simple. Lastly I encountered some major lag spots where there was excessive props laid out (the massive body pile in the screenshot above being one of them).
But I'm not going to say these things made the game terrible by any means. I still had fun and might play it again sometime down the line. In fact it had some of the best weapon placement in any map I've ever played...not too spaced out but still a small risk of running out of ammo just before finding another ammo canteen. The amount of movement, climbing and twisting hallways made this a lot of fun to explore every spot I could find and the darkness felt just right that made me want to get to a lighted area as quickly as possible!
Lastly on the subject of the ending...all I have to say is...WHAT!? No seriously that was my words exactly...WHAT!? 
I was so shocked by the ending that I can't quite state if it was good or bad...but I won't spoil it for others...play for yourself and form your own opinion there!
Over all it was quick, fun and worth a try. Congrats on a above average campaign.

Pros:

-Map variety
-Scenic
-Well placed paths
-Challenging in some areas
-Well placed witches
-Map 3 mini finale?
-Map 4 door switch

Cons:

-Rough start 
-Total lack of melee weapons
-Only 1 spare pistol and 1 Desert Eagle
-Floating text is useless
-Too many witches in prison (3 at once!?)
-Map 3 mini finale?
-Lack of many tier 2 weapons.
-Poor weapon placement

Conclusion:

The game started out good...creepy opening, great environment and awesome selection of paths to go around to get to your goal. But slowly some very bad parts started to rear their ugly heads as I continued. There were NO melee weapons, VERY FEW second pistol placements and ZERO tier two weapons besides the most basic from the first game (okay granted I found ONE Spas 12 and ONE military sniper rifle but thats it). There was also those random moments where you put in text indicating what was to happen in the level, but if you didn't stand in the exact spot they would either not show or would be blown up to a massive size making them unable to read, those really aren't needed. Lastly, while the placement of witches was very creative (behind closed doors, right in the way of where you needed to go and so on) there were honestly in my opinion just a few too many. I felt like I was in hard rain except no rain and the witches were being pains in my tookas. This map needs a review and reworking cause there are some serious glaring problems that need fixing before its considered great. Now I'm not saying its the worst I've ever played, no no no, there are maps FAR much worse and like I said, I liked the idea, but it just does need a few major improvements before I would consider it a good map that I want to play again. 
Give it a well deserved update and you have a map that can be a real fun challenge for the basic player.

Pros:

-Expansive.
-Unique desert theme.
-Entertaining finale.
-custom skins.

Cons:

-Over modulated voice (tone it down!)
-Very...yellow
-Hazy/dusty areas overdone

Conclusion:

Overall not a terrible map, it  has a very unique theme (desert, not often used), the between houses were fun to explore and it made for a good challenge throughout. But there are some glaring downsides. For example, yes its a desert, we get that but my god I don't think I have ever seen a desert this ugly of a yellow before...it looks a Jarate stained filter was covering the screen half the time. Secondly, its cool you decided to add the custom dialogue and all but it was painfully loud and half the time you could not hear what the guy was saying. Tone down the modulation on the voice if you ever get around to editing the map, lastly it was a desert I know, but the parts with the sandy or dusty clogged areas were a bit to much and had to tell at times where to go.
Yes I'm being a little nit-picky about it all but some one had to say something. Its a great map, don't get me wrong I had fun, but its not a map I'm holding onto (also I can't seem to find any server thats not modded to hell with it, had to play off my personal internet connection). Easily I would recommend people to at least try it, its good and worth at least one play through.

Pros:

-Custom skins
-Well placed Health and Weapons
-Very scenic
-Dark

Cons:

-Dark
-Some tight areas
-Very basic finale

Conclusion:

All in all a pretty good map! I had fun time playing through it and I would recommend it to others. If there was anything that I really had to gripe about was there were some very tight spots where a horde would suddenly appear as well as it being beyond dark at some spots...this is L4D2 we're playing...not Slender. Also I do have to agree with dguitarhero, the ending in a subway tunnel was pretty common and has been quite over used in most maps. 
Other than that, I rather enjoyed this and would easily suggest others to really give it a try at least once if you're tired of the same dull routine maps. 
8.9 out of ten.

Pros:

-unique dialogue
-winding pathways
-challenging
-good weapon selection
-decent finale

Cons:

-alarm run too long
-misleading
-confusing escape
-limited melee weapons
-Too many Tanks at end

Conclusion:

This was a average map...good in some areas bad in others but overall not the worst meanwhile also not the best. My main problem I had with this map was the slight lack of directions, there were arrows every now and then but in some major points I did get lost as to where to go (ex. huge  dumpster of sand, bar, and most of all what level I had to be on to jump to the garbage lift and back to the car.) Also the Alarm run was a bit long as I said above and finding the off switch was really tricky. This needs some work before I could consider it good but like I said its not bad...just okay. I do recommend it still to other players but be sure you are ready to give your fingers a work out! Consider some of the suggestions I made and this map could be really well done.

Pros:

-expansive
-challenging
-clever idea

Cons:

-slightly too open in some areas
-somewhat blocky design
-Dark, for lack of a better word, is good

Conclusion:

At first glance the campaign seems a little unpolished but once played through it becomes clear that I lot of work and creativity went into the design of this map. The whole thing greatly reminds me of the book, The Compound, by S.A. Bodeen, a post apocalyptic underground chamber that ends up being not as safe as one would assume. Throughout the map, buildings and other areas seem fairly simple in design but not terribly so and still make for overall fun gameplay. 
One major problem is how incredibly dark and it can be through some hallways...even the flashlight wasn't much help with what lay ahead of the player. It had a good enough challenge regardless of playing with bots all the way through and save for some really open areas the whole thing plays wonderfully. Definitely a map I recommend for people to at least try once! Kudos and keep up the great work!

Pros:

-PRESENTLY BROKEN!!!

Cons:

-CURRENTLY IN NEED OF REPAIRS!!!

Conclusion:

@Mr.llama: Due to the Sacrifice update this map, much like the Badwater map, was screwed up and lost a lot of textures thus making the game nearly unplayable. The author needs to look into it and have it fixed before its playable again. I'll make the post for future players and hopefully the author will take notice as well.



TO EVERYONE & AUTHOR OF THIS MAP:

DUE TO "THE SACRIFICE"  UPDATE, THIS MAP REQUIRES MAINTENANCE AND IS THEREFORE, AT PRESENT TIME, TO BE CONSIDERED DOWN FOR REPAIRS! DOWNLOADING THIS MAP WILL HAVE MOST OF THE TEXTURES FROM TF2 MISSING INCLUDING THE BOMB CART, TRACK AND OTHER PARTS OF THE MAP. DOWNLOADING IS NOT RECOMMENDED AND ANY PREVIOUS FILES OF THIS SHOULD BE REMOVED FROM YOUR ADDONS FOLDER UNTIL FURTHER NOTICE...APOLOGIES FOR THE INCONVENIENCE!!!

Pros:

-Very well put together
-Small changes for good game play
-Unique idea
-Confusing...but in a good way

Cons:

-Seems kinda short
-Sometimes too small of changes...
-Really slow and easy finale.

Conclusion:

Not a bad map for players trying to get into playing mod maps, similar enough to the normal map so your not utterly lost on where to go and cleaver changes that still make it show a difference from the original. Maybe its because I've played the standard map way too many times or I know it both forward and backwards that actually playing it backwards makes it kinda slow for me but I wouldn't call it the best map ever made by a long shot...but its still fun nevertheless. A lot more effort was put into this compared to your No Mercy map and way more realistic, but on the downside way less modded, so its kinda a fifty fifty toss up on the whole thing. Good job and looking forward to other reverse maps in the future should they actually be made!

Pros:

-Very challenging
-unique idea with the silo elevator
-well placed zombie spawns
-encroaching darkness feeling
-custom graffiti

Cons:

-Second level is way to dark
-Need more light in tons of places
-ammo a bit too far a few in between
-Screaming Gnome
-Campaign poster needs to be fixed!

Conclusion:

All in all a interesting map, unique areas such as the shipping yard and hotel kept me playing to see what else was coming and the elevator to the finale was fun to ride, until the tank showed up. Unfortunately I was really put off by the second level and how dark it was...I mean I know this game is supposed to be dark, but damn, I was blind through that part of the map! The small part in the sewers with the pipes could be a great section for a survival map as well as the chopper pads at the end. Going to the start I noticed a problem with the campaign poster you had, the names of the players we're all out of order...I was playing Bill but my name was under Louis' picture Zoey was labeled as Louis Bill was Zoey and Francis was still Francis...so might want to look into it.
So in the end this truly is a fun map to play if you want  a good challenge but does need a little work here and there and A LOT more light! Work on that in an update and you got yourself a right fine map here! Kudos!

Pros:

-Very clever even with feeling of incompleteness
-Twisting paths and secret holes make for a good time!
-Perfect map for a verses match...most of all with a charger!
-Could easily be made into map with some sort of environment...possibly frozen mountains?

Cons:

-Warning! Staring at the color Orange too long can cause migraines
-No music!
-Pretty bland...at least add an Blue sky skybox with clouds or something!
-INVISIBLE TANKS!?!?!?

Conclusion:

Played maps like this often on Team Fortress 2 and just like them this is a short lived enjoyment. Granted its fun and very unique but after awhile of running around endlessly in a maze of orange, things tend to get a bit tiresome. The lack of music was a tad disappointing...even some recycled music from one of the campaigns would have helped it greatly. This map has much potential to become even greater if you added a theme to it of some sort, as I suggested this site has very little in ways of Icy mountain maps and this would make an excellent one! I did have an issue where the bots started shooting at something in the distance and the growl of a tank but he was no where in sight! Then I saw a slab of concrete pulled up in mid air and I realized...oh holy crap...the Tank has a cloaking device! Maybe it was just my game, I don't know but it was creepy all the same. Good job on this my friend but really take my advice and get some theme on this baby. It can definitely go places!