Nice job!
What stood out the most was the core mechanic and the level design. It was definitely enjoyable and I had a good time working through the puzzles.
I think the audio (both music and sound effects) were little too repetitive and biting (something that sounded softer and had more variety would work very well for a relaxing puzzle game like this)
My thoughts on the art are the same as the audio. Maybe more variety and detail (I definitely get the minimalist thing you were going for, but the simpler the game, the more involved the surrounding elements tend to be).
Good job on an enjoyable game!