Some flaws
1. No instructions or tour of the app. 2. When you’ve correctly identified a chord, you don’t receive verification until you’ve moved on to the next one. So you’re looking at a smiley face (or frown) on a chord that you have not yet spelled and can’t go back to see what you got wrong or right. 3. Almost impossible to enter notes accurately on the miniature piano keyboard — correcting mistakes makes for rather slow going.