Other than the start being confusing escort mission at the start which everyone has already mentioned, the game is also way more difficult than it should have been (could just be I suck though), after the escort part, you need to be standing in the middle of the stage for obvious reason, and when that happens visibility of what enemies are coming is just way too bad, you have maybe 1 or 2 seconds window to kill each one after you saw them. And this includes time you need to move, aim, and spam the fire button.
So I definitely suggest you increase the size of the camera, other than that, having any indicator of how much the song left would be helpful, I was actually doubting if the song would end or if it just goes on to infinity until I actually beat the game so. Also, the holes acting as walls is just off, cause they kinda implies you could fall down, could had just have walls there.