This is a great concept, and when it works it works well, however as others have noted sometimes it will fail to load. To resolve this sometimes its as simple as swiping up and down on the Notification Center, sometimes locking and unlocking the phone, and at its worst, an iOS restart is necessary. Loading issues aside, one major problem that has yet to be fixed is the fact that the whole game is shifted to the right and is off center, at least on an iPhone 6. Cant speak for smaller or larger devices that I havent tried, but that is how it appears for me. Reinstalling the game does nothing either.
A feature request I would like to see in a future release is the ability to adjust the gravity and/or float sensitivity of the paper airplane. The longer you hold down, the faster it accelerates up, sometimes too much, and at time it doesnt feel naturally uniform.
Otherwise when the game works its quite fun. However these are still some major bugs that need fixed.