I saw a few videos of these with school kids using them to learn music, and the Thomann video is also very good to get an understanding of them. I think they are a great idea, also the colour coding to be able to tell the player which to one hit.
It sounds very cheesy, but we have had great fun as a family playing some tunes together with everyone having their own coupe of notes....... but it really is fun, trust me.
What we have found is that later on when the kids have had enough and they start hitting each other with them...... at least it is being musically!