I like the general idea of the game but it is far from polished enough to be playable from my perspective, I especially had a lot of issues with syncing the beats, such as the hitsound not being instant and thus being offbeat.
You can adjust the beat sync at the start of the game. As for the hitsound, it's played as soon as you press the button and it lasts for 0.1s I'm not an audio person so it was good for me, but I can imagine person with better ears to see the fault there
Actually you are right. I've just checked that, audio file indeed has a relatively long pause before actual SFX is played. Too bad I didn't notice that on time :D