The most useful feature of this app is the song composer which lets you pick one chord at a time to build your song. With each chord selected, the app will provide a number of chords to choose from for next step, and this is a great tool. Unfortunately there is a number of issues holding the app back and making it unworthy IMO of the $20 full unlock price which I paid. There’s bugs that effect the interface. For example, the keyboard display that shows the selected chords notes often fails to update as you select different chords. Layout issues where text elements get stacked on top of each other making it illegible. When composing, the app is obsessed with filling a 4 beat measure, leading to prompts that are intended to be helpful but really just inhibit workflow. And sometimes the chord you select is not the chord you get added, forcing you to delete the chord and try a couple times again until the app plays along. None of these are show stoppers, but the biggest disappointment is paying $20 to unlock different scales. After paying the scales become available, but there are no chords within those scales available to build songs. For example, I was excited to build a song using chords from a blues scale or Dorian, paid the $20 and found no chords in the composer available for those scales. From what I can see, there is no additional functionality provided in the composer after paying. $20 does indeed unlock features, but I found those to be basic, obvious and of little value. Certainly not worth $20. So there is a ton of potential in the composer part of the app, but not fully tested and a bit misleading in purchasing expectations. My recommendation is to use the free version until you exhaust its potential, then try another app. As it stands, there is no reason to pay for this app.