Pros:

- Amazing amount of detail.
- Great atmosphere.
- Some custom objectives here and there.
- Extremely polished... outside of a few pretty glaring problems.

Cons:

- The way forward isn't always 100% clear
- Seems to be pretty buggy; a lot of missing sounds, and the campaign doesn't seem to play nice with other music mods.
- Crashed while loading the third map (common problem with highly detailed campaigns). 

Conclusion:

This campaign has the potential to be something really special. 

Unfortunately, it's a little too buggy for me to recommend wholeheartedly to anyone; in addition to the game crashing while loading the third map, I ran in to all kinds of other oddities, like floating items in the starting safe room of the second map, and missing Special Infected music. The map maker did a good job putting arrows to help direct you to the goal, but sometimes, those aren't useful - I found some arrows in the mall that apparently pointed me in circles, and with how detailed everything is, it's really easy to walk right past some of the tighter corridors and not see where you're meant to go next.

I want to love this campaign, and I kind of already do, but it needs just a little more work to be considered truly great.

Pros:

Unique setting
Authentic atmosphere
Lots of custom assets
Beautiful visuals
Above average map design
Custom survivor dialog

Cons:

Got lost or turned around a couple of times, especially in the 4th map
Bots had trouble getting in to the cable car
Gas can objective for the finale is a bit spread out and tedious to navigate
Golf clubs in the first map look like they should be usable melee weapons but aren't

Conclusion:

Pretty sure I've been waiting for this Campaign since the original Left 4 Dead, and now it's finally here. And it was definitely worth the wait! Yama is a feast for the eyes, utilizing its Japanese setting to the fullest extent. While Left 4 Dead is typically known for North American towns like Pennsylvania and New Orleans, Japan is very different, architecturally speaking, lending Yama its own unique atmosphere that is completely different from everything else out there right now. Narrow streets, neon lights, and tall buildings dominate the early maps of the campaign, as Yama eventually branches out into more rural mountain towns and industrial areas. And it's all just gorgeous. I'm in love.

But it's not all perfect. The density inherent to Japan, the high level of detail in this campaign, and the tendency for each map to have tons of secret alcoves and split paths means on more than one occasion I explored down a path that I expected would lead me to some bonus items or something and found that it merely wound me back to the beginning of the map. That's not the end of the world, but I legitimately got lost in the third map, when the rooftop path leading to the next area wasn't made entirely clear - might I suggest a couple trees or something to try and discourage the player from accidentally jumping off the roof (while still leaving the roof open as a danger area for smokers and jockeys)? And while I appreciate the finale, where you work your way up through the hotel and must come back down again to get to the rescue vehicle, everything feels just a little too spread out. With Dead Center, the big mall area was easy to read and figure out where gas cans were - in the Yama finale, figuring out how to get to any given cache of gasoline takes a little bit more work than should be necessary. 

Oh, but don't listen to people who say the campaign is too easy - they can just bump up the difficulty if they want more challenge. That's what it's there for. I think the current item distribution is just fine the way it is, and is in line with the difficulty of Valve's own official maps. 

Pros:

Screenshots look nice
An okay concept

Cons:

Missing textures
Bots get stuck in some maps
Very basic lighting
Poor prop placement (I guess that's a plane crash?)
Insta-kill traps
Confusing layouts

Conclusion:

I've written reviews for this campaign before and they generally end up being removed from the site for some reason, but for posterity I'll say it all again: I'm at a loss as to why this campaign is so highly rated. An amateur effort from start to finish, 2 Evil Eyes is not a campaign that I like, which is putting it politely. 

You want challenge? 2 Evil Eyes has challenge for you, with traps that require trial-and-error memorization. Don't know about the trap? Too bad, you're instantly incapped and maybe even killed, all because you decided to check a cabin and didn't know about the comical, Indiana-Jones-style rolling boulder that would come barreling through the structure the moment you stepped inside. In a game where a single incap can mean the difference between winning or restarting the map from the safe room, this kind of "oops now you're dead before you even realized what happened" map design is ill-conceived and frustrating. There's no challenge or skill to it, just simple memorization, something that goes against the entire design philosophy of Left4Dead. 

Venture further in to the campaign and expect to witness missing textures (including one whole entire map with a pink checkerboard sky), simplistic lighting, and generally unclear level design. I spent nearly ten minutes running around in circles in an area near the end of the campaign because in order to progress I had to find a tiny, unassuming walkie talkie out in the middle of a giant, basically empty parking lot. It was so small and so out in the middle of nowhere that I must've walked past it several times without even noticing it was there. To make matters worse, Ellis got stuck on the corner of the very same map earlier on and wouldn't catch up to the rest of the team no matter how far away I got. 

I picked up this campaign because Valve recommended it on the official Left4Dead 2 blog, and I came away not just underwhelmed, but legitimately frustrated and bewildered. You could certainly do worse, but you could also do a way, way, WAY better, too. Ugh. 

Pros:

- Lots of great visual details
- Interesting concept, interesting locale
- Fun and varied for the first half...

Cons:

- ...but the second half starts to feel a little repetitive, with lots of similar corridors.
- Finale concept is interesting, but maybe could have been better communicated.

Conclusion:

I really, really liked the first half of this campaign. I felt like it was setting up for something amazing - there were a lot of interesting stories being told (the house with the ambulance I felt was particularly chilling), but once you get in to the army base, things start to feel a little too same-y. I passed through a few areas that felt a little too similar to areas I had already encountered. I realize that's probably "realistic" with how a real military base would be designed, but I thought it was starting to get kind of boring as the campaign winded up to its finale. I liked how the finale ended, but I feel like it didn't go far enough - something about the presentation rubbed me the wrong way, if only a little bit. 

Still, an above average effort, and something I would definitely recommend to others.

Pros:

- The campaign feels more detailed and more atmospheric.
- Generally more polished than the first one.
- A little less rigidly structured. 
- Some creative puzzles.
- A lot of impressive "Oh shi-" moments.

Cons:

- Not new enough; the campaign lacks the surprise factor from the first.
- More difficult in some mildly frustrating ways.

Conclusion:

The first Questionable Ethics was a transcendent experience. It twisted Left4Dead in new and unique ways that constantly kept you guessing as to what was around every corner. "Alpha Test" is unfortunately more like business as usual - though still incredibly tense throughout, nothing in it matches the shock and awe experienced in the original campaign. There's too much about "Alpha Test" that is too familiar - almost all of the traps from the first campaign make a return appearance, often remixed to work in a new context. The multicolored pictures that can reveal items or infected, the gas can mechanic, even the shaft with the falling cars all make their return. Nothing really blows your mind, though that is in part because you occasionally work your way through areas from the first campaign (often from a new perspective). There are a few new elements sprinkled here and there but by and large it's nothing surprising. 

Mapping is a little more polished this time around - there's a greater sense that this is a "place" and not just bare walls. It also feels less deliberately scripted - whereas the first QE was the kind of thing you could only play once because of how rigid the structure was, this feels more like a regular L4D2 campaign. It might actually work in Versus - there were more than a few places I caught myself going, "man if I was a charger, this would be brutal." It's a good thing the CPU Special Infected aren't very smart, but even then, this is a difficult campaign - perhaps more difficult than the first. There's a push-and-pull going on here, where a lot scenarios require survivors to spread out a little to safely progress forward. But spread out too much, and you run the risk of being incapacitated in an area from which you cannot be rescued. 

All in all, more of the same, just more difficult and polished. That's both a good thing and a bad thing.