Downloaded and tried it. Here are my thoughts. My opinions only, take them or leave them. I am comparing your game to others in the genre and what I like about them.
The graphics are really nice! Good job there
I don't like the music. I would consider removing it completely or finding new music. Flappy Bird has no background music, only sounds. Robot Unicorn Attack is famous for it's music and really sets the mood. The creator of Matchday Heroes said in his thread that they removed the music due to complaints.
I find it very annoying to play the tutorial. The constant stops makes it hard to play though. I would summarize the game on 2 screens and put an instructions button on the main menu. You could also put them on screen fist time the player starts the game.
1. Tap to jump. Hold to fly longer.
2. Going over rocks is 1 point. 3 points for going under them.
I would put the score counter in the middle of the screen, like in Flappy Bird. I think being aware of the score at all time adds to the excitement of the game. I'm not sure distance is even needed, but can be left at the top corner if you want.
I find the game too hard to play. Once you release you have no control and if you overshoot a small target you are likely to die because you run into something. It's also often hard to go under things because you have very little time to get out of the water. I think you should increase the distance between obstacles. Flappy Bird might be hard but you can tap the screen at any time to jump again. In RUA you have double jump and a dash move so you can get out of a lot of trouble. Unless you make a game as addictive as Flappy Bird you really want the player to play longer sessions like in RUA.
