Hmm, it appears I am only the second person, at least on Newgrounds, to finish the game. Is everyone else experiencing lag? It played flawlessly through the NG Player for me. The whole game took about three hours to finish, and I think the ending's pretty cool.
I preferred to use mouse controls as they allow more precise movement and have an easy way to stop oneself. The score multiplier was a good idea, and I liked trying to get the emerald gems for extra points, but you really should be able submit your score without ending the game. Still, very fun, and worth it to complete.