When it works, it works really well, coming together to make a peaceful experience not often found in games. When it doesn't however, it realllllly doesn't. The controls are very imprecise, so a run for 5 red fruit in a row from quite high could lead to no fruit and your bird stuck momentairly under the ground, in a rock, desperetly trying to free itself by turning out of a tree trunk.
Great for a free experience, but if you were to pay for this you'd need to ask why a game about flying, with poor collision control on ground/tree/shrubs, and imprecise movement, has it's core collectable scattered amongst shrubs and rocks at ground level, or in caves, when you fly a bird that cannot turn around, so that you're forced to make love with the rock wall or floor, consistantly. If your game doesnt handle the ground well, keep the bird in the air with floating feathers or something.