Awesome... 5 stars.
If I would be testing this game I would suggest to try:
1) Add small arrow at the "nose" of the "snake" so it would point to the direction the snake is going so the controls feel more responsive and eyes can react not only on the motion but on the arrow position and rotate snake accordingly to arrow. I hope I could deliver the idea.
2) Slowmotion when upgrades appear on the screen and pick them just pressing Left or Right once to choose the upgrade.