Marred by some bad decisions.
This game is fun, for the most part. It's hard, mostly because the controls are extremely touchy at first. That's excusable, because the controls are very tight once you get used to them. However, there were some things that really hurt an otherwise enjoyable experience.
-Reusing the same graphics. There is a time and place for copy paste, but this is not it. You had this whole "exploration of massive, dilapidated dungeon" thing going on, and then there's these cookie cutter items. Even one or two variations would make the environment seem much more real.
-Hit detection on the crow. I realize this is tough to program, but there wasn't any obvious way to tell which of the crow's body parts counted towards colliding with the walls.
-Those vent things. There's ZERO indication of how close you need to be to a vent for it to affect you. This was really frustrating, and resulted in blatant trial-and-error gameplay, which sucks. Always.
Aside from these three things, I really liked this game (and I beat it!). The art style is great, the interactivity of the environments is cool, the music is nice and moody, and the gameplay is solid. Good job.