I thought the game would get boring quickly, but the way the angles of the planes, the spawn rate, flying speed etc were varied helped keep things interesting. The obstacles that the planes had to avoid was a nice addition as well.
I felt the game had the right level of challenge. I failed a few times but it never felt impossible to complete and wasn't too easy either.
I think this would make for a good mobile game. You'd be able to use multiple fingers to move stuff about as well.