Pros:

-Finally a challenge on expert, making the official campaigns fun to play again.
-It is very balanced even tough I imagine the run of the mill player having problems reaching the saferooms and would say otherwise.
-Tank music is awesome, hums along every time.
-Alterations in the finale eliminates often used strategies.
-Spawning tanks behind the player forcing them to flank backwards or run for dear life is brilliant.

Cons:

-At times there are minor bugs with the spawning of bosses including double spawn of witches for the entire level and nav issues that could be exploited.
-Spawning bosses in plain sight is not nice to the player, but these spots are avoided by trial and error.
-Electrified buttons can be avoided but there is no hint of how to do this.

Conclusion:

This bundle made the official campaigns worth playing again, which I for one haven't touched in a couple of years.
These campaigns are not suitable for beginners by any means, but if you have a friend/friends that always complete campaigns with ease on expert and know every trick in the L4D book, this is an awesome addition to the addon campaigns!
I really would love to see the creator(s) release similar HEM versions of The Sacrifice and Crash Course.
10/10 addon in my book.

Pros:

-The Gauntlet event was really fun, introducing an element that L4D1 users didn't originally get.
-A lot of custom content
-Original, no copy pasta work here I tell you!
-Difficult (some may say it's a con, but it's in the pro basket for me)
-Atmospheric and a great sense for detail (the big well lit pipe underneath the walkway was so beautiful I stood still for a minute just watching it...seriously)
-Lengthy, even though there's a map left to be done it's already a huge campaign.
-Survivor dialouge, it does a lot to the campaign feeling

Cons:

- No time to prepare during the finale
- A couple of models were as if drawn with toolsblack texture
-A scarcity of throwables in a couple of maps
-Lesser bugs

Conclusion:

An already splendid campaign and there's still one map to come. The pros heavily outweigh any cons which are confirmed to be on the "to do list". I appreciate the amount of time you spent mapping this campaign and sincerely hope that everyone who downloads it takes a moment to perceive the amount of time he spent mapping this campaign.
A straight to addon list favorite, which will be played in cycles with the other top campaigns there are.

Pros:

-Really hard!

-Lots of tanks

-Long levels, which aren't repetetive

-Interesting cihoke points

-Lots of throwables

-No missing textures

Cons:

-Can't play through the whole campaign due to floating spawning error on map 6. Need to restart the finale from the lobby everytime.

-Some textures look stretched

- The 3D skybox doesn't have the same fog settings as the actual map which looks weird.

-Idiotic bots, not really your fault though

-The music doesn't work as it should

-Confusing at times, first time plays only

Conclusion:

This is one of my and my friends favorite campaigns. We love playing it on expert due to the difficulty. It provides a real challenge that not many campaigns do. The campaign style is consistent and the events are varied. The pros heavily outweigh the cons, but if some of the cons were to be fixed it would rock even more! Actually, if you just fixed the map 6 spawning error and changed the level_sounds.txt files I would be happy as it is. 
The other cons are just nitpicking on a really fun and hard campaign. Thank you for the time spent creating it, I know what work lies behind a project such as this! Had many fun hours playing it!