I really enjoyed the game, it is probably the most relaxing game I've played without feeling bored after a few levels.
However, I tend to get really invested in anything when I'm receiving some sort of "grading", and even if that makes me enjoy a bit more the games, in this case it felt so stressing trying to figure how could I get 2 or 3 stars, specially when after a while I can't figure out a right answer (for example, trying colors with the books) and the hint is pointing me out the method I already got right.