Honestly...
The ideas are very good, the execution is terrible.
The Difficulty this add-on brings to the table is just artificial, everything is too aggressive and too fast to the point where the main strategy is to hide in a corner and just spam your pistol in heavy mode, the moment you decide to play this game like Doom or even D4T is the moment where you receive a swift death, it's a bit of a shame because I really do like what's added... I just hate how ALL of that is being Spammed at me as soon as I load a map.
My biggest gripe is all monsters notice you at loading a map, pairing that with how fast and aggressive they are on top of knowing a Lost Soul will always spawn is going from 0 to completely overwhelmed and you only have a pistol and chainsaw and it's only Map 1.
I'd suggest taking all the monsters down about 5 notches, to where they are noticeably more aggressive than D4T, but only slightly faster in most cases, the new attacks are more than enough to add more difficulty. The Lost Souls needs to be tweaked to a point where the spawn rate is someone what uncommon and delay it a bit to add the element of surprise. Tweaking Stealth and In-fighting accordingly to a point where the player can still utilize Glory Kills, and classic doom strategies, but have the approach shaken up to where you can be overwhelmed.
I like this mod, it's just severely unbalanced.