Very beautiful visuals and great sound ambience!
The UI is also great! Simple but effective.
I didn't understand what was the advantage of using different colors. I think red was the fastest and didn't run out of energy so I just stuck with it until the end after trying the other colors for a bit.
The flying is fun but it gets a bit repetitive after a while. It took me 11 minutes to do a full clear. I think having less Otomos to make the experience a bit shorter and enjoyable would be nice.
As some have pointed out in their comments, the controls cause a bit of strain on the hand so a shorter game session would help on that aspect as well.