And it is funny to think that they at a later date want to charge 8€ / 10$ for this.
To be favorable it looks good and you can see it as a guitar class or two if you are a beginner, and for this think that 2,28 € is okay- But it is not necessary as all this app is, is ten different instrumental tracks in the different keys with a diagram of the five different positions of the pentatonic scale.