I like this game. It feels very polished. Maybe the concept of the game is not new, but all the elements of the game are nicely implemented and work together well.
Of course the game is very hard, but i guess this is part of the concept.
I have given only 4 stars because there is still room for improvement:
* The second level seems to be much easier than the first. Also, there should be more levels
* While switching from Porpus to Gerios makes the game slightly easier, it becomes ridiculously hard after changing to Ura.. unlocking this bird feels more like a punishment than a reward.
* I suspect that certain spots in the levels are impossible to pass without taking damage... this just feels unfair.