I agree about the triggers being predictable. I have to admit I was a little disappointed to find out that the monster encounters aren't random. (I was told by a friend that they were.) It would have added replay value as subsequent play-throughs are more or less exactly the same experience. (Still fun though! I just really enjoy the engine.)
Towards the end of the game I found that I was forcing my excitement a little, as after you die a few times you realize that there really is no consequence for doing so. Also, the insanity mechanic, while cool (I wouldn't remove it.), doesn't really affect you all that much. You can play the whole game without using your lantern once, and without using one tinderbox. And just like when you die, you won't suffer any real consequences. These are minor complaints as I thoroughly enjoyed the game and all of it's mechanics. There just could have been more of a point to the mechanics.
For me, the only thing I would remove or change about the game was the dead bodies and Aggripa. The castle looked great, really believable. But the dead bodies looked corny. (The severed body parts looked fine though.) There wasn't anything scary or even grotesque about piles of dead, naked men with their funny looking fellows exposed. The polygon count was just too low, especially on the faces. I'm sorry, but it broke the immersion a little for me.
And the way Aggripa was just standing there, being friendly and giving Daniel instuctions threw me for a loop. The game had a great sense of isolation right up until there was a mission-giving NPC before me. Minor complaint... but still.
EDIT: But I totally disagree about the puzzles being too random! I found the puzzles to be fairly logical and never too obscure to understand. When I got stuck, it was only long enough to make finally solving the puzzle that much more satisfying. (Perfect for a puzzle game IMO!) The only time I became stuck for too long was...