I really had a good time with this. Very beautiful vibe, and really solid design work on the puzzles. This is more of a personal taste thing, but I would have appreciated if the gameplay gelled a little more with the story. To me, they felt like two separate entities. Both very good, but kind of in the way of each other. I also wish it was a smidge more challenging -- perhaps limiting the number of moves. But I also think that would get in the way of the story, which further adds weight to my previous point.
Still, I love the escalation of the puzzles and introduction of new mechanics. You understand basic game design principles, and that's a hard thing to get right in a lot of cases. Beautifully done.