What it teaches
Where countries actually are, which is the fact a flag quiz cannot give. A child can know the Italian flag perfectly and have no idea that Italy is the boot.
The map is drawn from Natural Earth data, so the shapes and the borders are the real ones rather than a cartoon.
What to look for
Start at level 1 even with an older child. Thirteen countries that can be found confidently is a much better foundation than thirty-eight that cannot.
The tapped country is marked with a tick or a cross as well as a colour, so a child who cannot separate the green from the red is not left guessing.