Very nice, a simple but fun game design. Clever, because it will mean making new levels will be pretty simple to do.
I played through to level 11 in one sitting, but had to call it quits there its very challenging - I’ll try again later 
Personally I found the controls easy and intuitive to use, but I would be interested in trying the other controls you described (left right screen regions / swipe jump)
The game performed well on my S4 (given it sounds like you are testing on a S2 that’s not surprising) the player character does get a bit jittery when moving fast in one direction though, the clouds were still moving smoothly.
Do you have plans for collectables? I noticed with levels like level 8 you can actually take a slightly easier path by balancing the ball rather than trying to knock it over the top, having collectables along the top route would reward people for taking that path over the easier one which makes it more competitive and give it a higher replayability.
How about moving platforms in later levels? I could imagine a spinning platform with 4 prongs could be an interesting challenge.
In terms of aesthetics, I do like its simplicity. Here are a few ideas you can take with a grain of salt. Secondary motion on the player would be nice, a bit of drag on his claws, and maybe even some subtle rotation of his body when he is moving and overlap when he jumps and lands. It would be good to get his little feet moving as well, even if it’s just up and down in alternating pairs. I love how his eyes follows the ball, maybe even put a blink in there when he hits the ball from a great height. Parallax on those clouds would go a long way aswell 
Its a shame about the engine size, the size of the download was something I noted straight away.
Sorry for being so wordy, but I think it has a lot of potential and am looking forward to seeing more developments!