I loved it! The aesthetic is super memorable, the length is just about perfect. I absolutely prefer this bite-sized package to obtuse first-person-puzzlers like The Witness or even Talos Principle. For me, those are like suffering through a bland soup just to get at a few good meatballs. This was like a delicious plate of pasta - just the right length to leave me wanting a bit more, but also easy to share.
I had to watch someone's Let's Play to figure out the wood beam to jam the door. Mechanically, it just seemed a little out of place as it was the only time you really use an object from the environment that doesn't seem like a key. But maybe my missing it says more about me than the puzzle, I dunno. (It took me a while to figure out I had to push the box over with that board too, but I did get it.) In general, there aren't really any red herrings to the puzzles, and I felt like I had all the tools I needed, which I really liked.
Other notes since it's fresh in my mind:
Everything looks wonderful. The fox animation was super great and even the orbiting of the sun made this feel a lot more "lived in" than The Witness. Which is maybe ironic since the white-heavy palette could be considered sterile in a way, but the way everything is kinda settled in, leaning on each other, also makes it feel like objects here have a story to tell. They're not perfectly erect; something has happened to them.
I also really like the notecard system, the actual notes themselves, and the way you can pick up and rotate objects. I liked the motion blur.
*one other minor, minor gripe: I got caught on the doorway coming up the stairs several times. urgh!
Anyway, kudos to you - can't wait to see what you work on next. I felt compelled to play it as soon as I saw a screenshot of it, I was compelled to finish it in a single sitting, and I enjoyed just about every moment of it. That's super rare.