The text only shows up if you don't submit a link. This really threw me off for a while.
I played the game for five minutes -- I think I'm better than average at playing new games and I found it challenging. You want more of a learning curve. I would recommend making the loops bigger. I hit the sides of them too much. Maybe you can make them smaller again on later stages. Is the game too easy if you add a continue button, or passwords?
Also, do you get bonus points for doing loops? I'm not sure how the chain concept works. Is there a limit on boosts? These things aren't really clear. A tutorial might help, though I know it's better to put the player right in the game. When I initially started, I crashed into the ground twice. You should detect for this on first run and pop up telling the player that up is down and down is up, just like a real stunt plane.
Technically, you guys did a good job, the game seems to work flawlessly. One tiny thing I notice is that when you end the level while still flying vertically, the plane corrects itself pretty harshly. I think it would look better if you slowed that animation down, or maybe made it always finish in an extra loop... or don't take control away from the player and let him crash the plane if he wants.