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.