Love it! It could be even more awesome if the velocity of each key press had an impact of the volume, that way we could control two properties at once.
Velocity is controlled by where you tap the screen (vertically)
Ah yes indeed, but I don't think it can be controlled if you're using a physical keyboard. For instance if I play using the keypad on my keyboard, 1 could be pianissimo and 9 fortissimo.