Nice game.  I liked the "Insert Coin" on the start screen.  Nice touch :-)  I particularly liked the orange "coming next" indicator.  That was very interesting and I found myself looking at the orange indicator more often than the green one.

Perhaps more of a punishment for not hitting the right key.  As far as I could see, getting it wrong just didn't move on to the next hole.  If you lost time, or had to restart the level, that might add a bit more jeopardy to the frantic button pressing :-)

As I said, nice game, well executed.