Good in concept...
However, the lack of a strike line (even a strike line for each individual row) bumps the difficulty in a fairly artificial way. While it might be nice to be able to prove you know a song well enough to have the strike lines turned off, it shouldn't be the default. Think DDR and dark mode.
The fact that the key presses are along to the beat but the firework 'pop' is off beat is just further artificial difficulty. Either kill the pop sound effect, or time it so that it's on another beat.