I absolutely love this :)
The animations were great, so was the music. The way the music kinda followed the difficulty spike was a nice touch.
But man, what is the helicopters' problem :)
The only thing I would add is that the lighter coloured bird was hard to spot, especially against the clouds. The other thing I thing would be better is the option to somehow skip the restart sequence. I mean its lovely and funny, but I saw it like 30 times :)
Other than that I have really nothing bad to say about it. Some details to add could be floating health somewhere. And maybe make the rocket look more and more beaten up as you lose health.
But I really enjoyed playing this. I haven't beaten it yet, but I will :)