Pros:

-Awesome zombie spawns
-Zombie spawn traps on doors
-The hallway chase 
-Several "WTF just happened???" moments
-The moving car

Cons:

-Zombie spawns are broken as hell. In some cases, they can warp right on top of you
-Intro is a little choppy/rough
-Tank can step into the helicopter (this personally screwed us over in our video review)
-Massive zombie spawns can be hard, especially on higher difficulties
-(more situational than anything) Zombie spawns in general can sometimes be buggy. A specific example is the 1st map, where the director can spawn massive hordes of zombies, or none at all (though this is rare)

Conclusion:

If you're looking for a map for zombie kill achievements, this is the one for you. If you're looking for adventure, excitement, and all-around fun, this is the one for you. If you're looking for an easy map with few zombies and working spawns, you're out of luck: this map is the definition of broken spawns. 
Regardless, it's still very fun, despite the spawns being broken. Playing on Expert will get you killed easily. Normal/Advanced is the way to go. Overall score of 75.
Video review can be viewed on Youtube, titled "Left 4 Dead Episode 10 - How To Fail At: Strandead". 

Pros:

-Traps everywhere!
-Dark atmosphere, meaning that special encounters get scarier
-Lots of "WTF just happened???" moments
-Lots of thinking involved
-Large horde sizes

Cons:

-Several traps require multiple restarts before success
-Certain safe rooms can put you into an infinite free-fall, requiring game restart
-Traps often instant kill the AIs, making solo mode a real challange
-The crushers on map 5 can be problematic for several players

Conclusion:

This map is a hell ova' lot of fun! Traps are well placed and well executed (and well executing!), atmosphere is perfect, and the map is fluent & linear. However, large horde spawns and many "insta-kill" traps can lead to multiple restarts and AI deaths. This is certainly one of those maps where a friend is required, unless you want to be restarting every few minutes. 
Overall, however, the map is very well designed and highly recommended. Just don't try it on anything but Normal or Easy, unless you have an elite team of 4 players with good ping. Overall rating is 85.
Video review can be viewed on Youtube, titled "Left 4 Dead Episode 9 - How To Fail At: Powerstation (Parts I & II)". 

Pros:

-A unique map, indeed
-Many surprises to be had. The flying rocks were my personal favorites
-Alan especially like the "Gundum" reference (I pray I spelled that right. He'd have my head if I got it wrong...)
-First aid kit and ammo generation every minute or so

Cons:

-For me personally, it's sometimes hard to get the map started. Alan seems to have it down pat, though
-AIs do absolutely nothing to help, other than heal you occasionally
-The truck boss can potentially wipe out an entire team if caught off guard
-Chopper/army truck gauntlet can be hard to survive
-(not necessarily a con) Difficulty function serves no purpose other than friendly fire damage

Conclusion:

I personally recommended this map for our series. It's quite fun to blast away flying cars that shoot balls of plasma at you. Seriously, I can't think of a more original concept. One shotting tanks with the hunting rifle is fun, too. However, due to the lack of AI functionality, I recommend playing this one with a friend. Be warned that going this one solo will greatly increase the difficulty, and you'll be fighting the final boss for a long, long time. The only other thing we would have liked to have seen is a difference in difficulties, like if the plasma balls did 10 damage on Advanced/Expert instead of 5 damage. That sort of thing. Also, another map or two would have been nice, but we're not complaining with what is provided. 
Overall, Alan and I agree that this map is a keeper, and sure as hell is a lot of fun. Just be sure to play with a friend or two. Ratings are 80-90 (85 average).
Video review can be viewed on Youtube, titled "Left 4 Dead Episode 8 - How To Fail At: Space Harrier".

Pros:

-The radio broadcast intro was very nice, and set the atmosphere for the events to come
-The train transition between maps 4 and 5 was excellent
-Bots don't get stuck (at least, any more than they usually do)
-Finale location is perfect
-An overall official Valve map feel

Cons:

-The finale, on higher difficulties, can sometimes be annoying
-The finale helicopter can sometimes "push" players into harms way (may be situational) 
-Auto-dying when falling off the train on the 4th map. Can be easily exploited in versus and is nearly impossible to recover from
-(while not necessarily a con) Many "point of no return" areas can easily lead to player deaths if not properly countered

Conclusion:

This was the first custom map for our "How To Fail" Series, and with good reason. This is the closest thing to a Valve custom map as you're going to get: a map with a linear flow while retaining enough surprises to keep you on you're toes. As stated before, the finale location is quite good, but can be a pain to get through on higher difficulties. Overall, Alan and I agree that this map is excellent, both for it's straightforwardness and it's official Valve map feel. Overall rating is 90-100 (95 average).
Video review can be viewed on Youtube, titled "Left 4 Dead Episode 7 - How To Fail At: Suicide Blitz".