Loved the music and the atmosphere. The sharks surrounding the island was a pretty clever; leaves no thought for escape, only survival. I also quite liked the graphics and the attention to detail. The trees and other tiles were nice to look at, and I noticed that the strawberries only grow on grass. Knocking coconuts out of the tree is pretty fun, too.
I do wish I could do something with the materials collected though, didn't really understand why I was collecting them. And on Day 4 I believe, when it tells you to "Store food", I truly didn't know what that meant and just spent most of the day looking for like a chest or something I could store food in, only to finally realize that it meant I needed to collect food. I also wish I could sprint in exchange for hunger. I'd just like to be able to move faster. Overall though, I felt the size of the island worked well with the speed time moved at; I was able to explore the whole thing within the 4 days.
Also, maybe you could give the player a minimap that gets filled out as they walk around? It was a bit difficult to find the shelter sometimes. I enjoyed my time with the game, nice work :)