That looks like the kind of puzzle I'd enjoy.
And it just so happens that the color of my tile floor is mostly the same color gray as the backside of puzzle pieces, so we've "lost" pieces that end up being found minutes later when we hand-sweep the floor and they flip right-side up.
If they are actually lost than we mark the front of the box with the number of pieces missing so the next person doesn't feel they've lost them.
CathyA and other puzzlers:
I'm curious if you like to do crossword puzzles or Sudoku/number puzzles too? or is it just picture puzzles? I've gotten more into crossword puzzles and my SO is into KenKen and Sudoku and I'm wondering if that's all connected as enjoyable hobbies.