I like how the puzzles become challenging while still being simple.
I would like to have an undo button, I make a single mistake and then have to redo the entire puzzle. Also, the input seems to lag a bit, especially when the levels start.
I've actually found a couple other puzzles where that happens too.
Some of the tv puzzles don't scroll the screen when I walk off the edge, then I'm trapped in the side after I walk back. Thankfully resetting the puzzle still works.