The music is the biggest offender here (Also fuck those crickets), out of nowhere it will start playing loud music in an attempt to build tension or something for the entire level. This does not work. I spent the entire time expecting something to happen, and I wasn't let down, since every five minutes I was faced with another half second jump scare.
As far as everything goes it seems like you took a lot of inspiration from korsakovia, decent story basis, awful level design, no pacing, and all. Almost every puzzle I encountered before quitting at the part with all the tubs, was either trial and error, solved by some irrelevant means (Lady with knife in her back drops key when you touch the knife? What?), or just downright too clever to solve without stopping for 15 minutes and getting frustrated.
Frustration breaks immersion(And it really didn't help that the story was all over the place, too many random characters, it was really hard to recognize the important characters and events, let alone remember them for more than 10 minutes), and literally every puzzle makes the player stop at a locked door, and then search around for an unintuitive answer. If the player is too busy being frustrated, he's not going to be able to focus on the story. I had to find a walkthrough almost every time I faced a blocked path, and those players had the same issues I did.
The lighting really needs improvement too, everywhere I went was either too dark, or so well lit it wasn't scary at all. (Box lights covering the whole level at 0.1 brightness maybe?)
This was impossible to navigate, don't use such thin transparent grates, I spent about 5 minutes trying to find a secret path around, only to find out that the way I was supposed to go was right there the whole time.
http://dl.dropbox.com/u/3332789/Amnesia/...agrate.png
You also might have been better off having less batteries, that carried more of a charge, I have no idea how my flashlight holds about 6 of them.
Finally, optimization, (Intel Core2Quad Q9000, Nvidia 9600M GT, 4GB RAM) or the lack thereof. I ran the mod at the same settings I run Amnesia (at 40-60fpsish) at, and quite frequently I was seeing 10-20 fps streaks, which is odd, since the level of detail in the levels was way lower.
Anyway, the voice acting is ok at worst, and pretty good at best, could be better in some places, but I know too well how difficult good voice acting is to pull off, so I'll give you points here.
It was cute how you replaced tinderboxes with lightbulbs.
I couldn't shake this feeling as I went on that you started the design at the beginning, and learned as you went on, since the environments slowly did get better and better, and near the end what I saw in the walkthrough I watched after I quit things started looking pretty decent, so I'm more than a little tempted to continue now that I know how to solve the puzzles.
Despite everything I've said it's not all bad, I definitely hope you make another story driven level, but this time keep the infuriating puzzles out. Having puzzles that are too easy isn't a bad thing if you're trying to make something that plays like an experience. For instance the bricks revealing platforms is intuitive and clever, you needed more of that. You also have some really neat effects (chains blocking the path near the end for instance), and the story does have it's moments near the end where it really comes alive.
Anyway, I apologize for this feedback not being as focused as it should be, I wrote it over the course of an hour and a half while still watching the walkthrough from where I left off to try to ensure I forgot as little important information as possible.