Hi, I played through quick and jotted down some first impressions...now that I re read your post im not sure that you asked for that or even want that, If I annoy you let me know and I will delete this
Nexus 6p Android 7.0
The background image of trees on the very first screen I am greeted with are stretched, this gives a quick first impression that something is broken (although everything works great)
The instructions image was not clear enough for me to blindly pickup and play. I found myself swiping repeatedly to fly, nothing happens, confused, pause and re-read, and realize swipe to set angle and tap repeatedly to fly. I like that the instructions are not overly complicated, it just didn't translate at first in my case, maybe just me.
It is too easy to tap too much and fly completely out of view, the camera needs to follow better and/or set speed or world boundaries.
The entire app plays very smooth on my device except one spot, there is a slight FPS hickup/freeze when the bad bird attacks, (bird hits, feathers fly and "get ready" is displayed)
When I hit pause, there are images that I can swipe through, the list gets bigger, I don't know what these are, screen shots from each previous time you hit pause? but anyway I can swipe left/right on the image to cycle through, but I have to swipe on the image itself, swiping the screen anywhere else does not allow me to throw it, but I can see an indicator that I am supposed to be able to swipe, felt broken at that very moment.
on the email/contact dev screen the list of email subjects, the list itself is off center.
The device screen turned off after a short period inactivity, I personally like to keep the screen awake during a game but I might be wrong to do that.
The art needs improvement. ( not trying to be rude, I personally have only released stuff with really shitty art and its just kills that 1 second first impression that is so important).
once I figured out what I was doing wrong and figured out how to play I liked it very much, but in a real world scenario I would probably start swiping, nothings happening then i would probably just delete it not giving it a chance because people like me play games like a neanderthal.
Test fairy is a great free service for testing, you can record video of the game play with touch points so you know if these mistakes that I made are common or not. (the video recording does take a big hit on performance).