I have some nostalgia for this mission. It's well designed in some respects and pulls of some interesting effects. It's also got an enjoyable story. It's large, laid out well, and crawling with Hammerites, which I love! It's a bit of a puzzle and and a healthy challenge.

However, that is not enough to save this mission from the recycle bin. The bugs are awful. Listing a few here:

Guards that cannot be knocked out (not a helmet... blackjack goes through his body). I believe this an effect caused by spawning guards in right on top of you (explained further)

Picked up a guard and couldn't drop him. Broke the save. Had to start all over.
This same guy will actually become frobbable before knocking him out. You can pick him up in the middle of combat and he disappears from the game world, but you can't drop him ever again. Have to start the mission over if you do pick him up.

This forces you to knock him out in a very well lit area and leave his body for multiple guards to find every time they path through.

Readable like parchments are set to show on screen rather than open the page. This is nice because it doesn't change the interface to read what is inside, but the amount of time you can read is like 5 seconds. I have to keep clicking each scroll several times to keep reading the whole thing after finding where I left off.

a guard spawns on top of you as a trigger when you open a door. This guard cannot be knocked out or killed if you do manage to miraculously avoid him. You are forced to be seen by him and then can only use flashbombs or gas mines. This gimmick is used at least 3 times and is annoying because it breaks stealth and forces save scumming.

at least one AI was found in a t-pose.

And the most condemning, this mission cannot finish using Newdark. There appears to be a separate issue where the game is not finish-able on expert, but the Newdark bug is a different one. Somehow the incompatibility with Newdark causes a stone wall to appear blocking access, only in that version of the game. While it might be tempting to blame Newdark, This doesn't happen with missions that are setup correctly.

And with all the level-breaking bugs, it's simply not pretty. The solid gray stone color pallet becomes your enemy much more so than the Hammerites.