Really impressive! It's simple, but really well implemented.
I would say the difficulty was a little challenging for me personally, but take that with a grain of salt. I absolutely suck at puzzles, but I was still able to get to the end with a little trial and error. It didn't take me very long overall so I think the difficulty is probably fine for your target audience. My highest number of attempts at a single puzzle was no more than 10.
The tutorialization was, in my opinion, just the right amount. Not too much hand-holding, but I also didn't feel like I didn't know how things worked.
I honestly wracked my brain looking for a critique, but I don't know that I have one. No bugs that I could find.