The bird IS a worthy investment. It basically DOUBLES the replay value of the game. They only marketed it wrong. They made it appear as a handicap to help you solve hard levels.

In reality, it provides a new puzzle for you to solve on EVERY level. On some levels (such as the first few), its easy to achieve 100% demolition and earn a feather. But later levels involve using some regular birds first to reach some far-away blocks, before calling in the big eagle. I've heard of many levels where people are stuck at 96-99%. Achieving a feather in every level will be a difficult task.

And the 1/hr rule only applies to levels you haven't beaten yet. Once you beat a level with the normal birds, you're free to use the eagle as much as you want to earn your feather.

I definitely will be buying the Might Eagle for a mere buck once its ported to the Droid.