Ooh, I really really enjoy the visuals you got going on, it looks super pretty! I think you also did a really great job with the UI, it's really visually appealing~ I like that the idea is relatively simple, but it works very well in the execution!
Something I would have liked to see, though, is maybe a sort indicator of where the cannonball is expected to fly towards? Maybe it's just me, but I felt like there was a slight disconnect between where I was aiming + how much I was charging up, to where the cannonball actually flew to in the end. But aside from that, it was really nice! :D