You clearly put a heck of a lot of work into this because it shows. The art was very beautiful, the sound and music created the perfect mood, and... well there's not much else to speak of sadly. Some of the animation was quite jagged (mostly on the limbs) which was distracting. I didn't feel like it needed to be as long as it did; I often found myself daydreaming because the pace wasn't very engrossing at all. The story was cheesy and the monster, like someone said earlier, was kind of silly. It didn't have to be though, you could have saved yourself a bunch of work and just kept the monster hidden. That could have made for a potentially more interesting story and kept some of that much needed suspense. Those are my personal feelings though, maybe you intended to present the monster as more of an imminent threat, I just don't see the purpose in that.