I'm just going to put it straight out there: The music in this game is seriously creeping me out. I know it's a scary forest and everything but damn there should be a warning label for that soundtrack.
Design (1/5 jumps) - The design of the game could use some improvements which I will specify later on.
Audio (2/5 creeps) - As I mentioned, I got the creeps just from listening, I firmly believe you could find a better soundtrack to set the atmosphere for this game especially with a cute turtle being your star. Not to mention, the fish and sword sounds could use some tweaking to be more coherent with the overall atmosphere.
Mechanics (3/5 fishes) - To be fair, I think most of the mechanics in these kind of games are more or less the same and you have that mostly down. Just work on the implementation.
Art (2/5 castles) - The turtle's animation is rough and the background could definitely be better as something the user wants to strive to see.
Unfair (1/5 swords) - Some times it is out of pure luck that I get as far as I do and then at some parts I have absolutely no way of continuing no matter my skill level. It becomes more a game of luck this way which I think needs to be changed. You could always check out how your competitors like doodle jump have implemented their game mechanics to make the player always feel in control.
Slow Progress? (2/5 turtles) - I understand the you are a turtle and all but I think, at least with the current mechanics, that the turtle could follow the mouse fully instead of slowing moving towards that location. Other than that, it feels awesome in some games to have a huge boost when collecting multiple fish because you get to shoot straight up. However, this game limits you to its screen that's slowly progressing upwards, I think you could take some ideas from that.
Long way to go but at the very least you have the mechanics sorted out. Don't give up!
Fly your own turtle to the top right here: Grumpy Turtle