So far the puzzles, monster encounters and loot seems to be greatly balanced (which is not common for mods IMO). The story evolves nicely (I love reading those notes. Can't wait for next one) and visually the dungeon is well executed (not only custom props, but also overall level design). I'm sort of sorry it's only four levels (but hey, it's quality not quantity that counts!).
I have only two concerns so far (some nit picking only improves creditability of my above praises

One is about skulls (organic ones, not crafted object from gold or crystal). They do not count as skulls for Head Hunter trait. Is skull bonus hard coded? It would be great if they act like regular skulls. Skull collecting would get much more personal if you know the name of former skull "owner" and circumstances of his demise.
The other one is about locks. The original keys and locks were paired by colour or shape and it seems logical. I spend quite a long time trying to open brass locks with brass keys and round lock with round key before I realised you mixed them all. It's not a big deal but I'd keep the original code unless you make totally new keys, but even then I'd rather keep to the rules that emerald key opens emerald lock and so on.
- The lever on level 2 (the room with torches and two snails). I have this horrible feeling I've missed something cool.
- The rune button in that upstairs part of maze.
The bad thing about mods is you can't look for walkthrough on GameBanshee

Also there was that room on level 2 with lots of pits that you can see by windows (BTW your windows rock! Good way of tease players or foreshadow future challenges) but I guess it's still ahead of me and I will get back there from level 3. Will I?