I see this is your first project, it's a nice start.
The music was well matched with the game.
Once I got stuck in a wall, it happened while I was moving very quickly and changed direction. Colliders can be tricky to use and these glitches are very common. Try to check Unity's manual or some tutorials and experiment with the rigidbody / colliders settings.
Also, if you don't press any key billie will just keep going in the same direction, apparently at the same speed. By adjusting the linear drag on the rigidbody you could probably achieve an effect that feels more like water friction.
Hope it helps.
Feel free to check my entry, any feedback is appreciated.