You're a music producer putting together a song in your choice genre, but you don't like what you hear. What do you do? That's right, pull out your guns and start shooting the notes out of the air.
The premise of Guns and Notes is almost entirely irrelevant to the game. Not much time is spent setting up the narrative, and once you're in there, it isn't really important. The aim is to shoot music notes out of the air, but you could be playing any other VR shooter for all the difference it makes. Which isn't to say it's necessarily a bad game. You can play your own tunes and take on those pesky music notes in a variety of genre appropriate settings. There's nothing in the way of game modes and challenges, so don't be prepared for much more than the basic shooting experience. The theme of the game creates an expectation that it should be in some way a rhythm based game, but that's not the case; there's no link between the game and the music.
The game is essentially a "pop the balloon" simulator with a different skin. It plays this role fine, but there's not much more to it, and there are better versions of this available.