Updated review: Yesterday I removed the broken app, and today downloaded it again. This time it installed, then worked flawlessly. The info is gold for beginners as well as advanced vocalists, and I do recommend the CVT book as well. When it didn't work, I was worried that I had wasted my money, but today with the new install, it turned out to be a very good buy.
Impractical. It packages the book of the same name for 50% greater cost with the benefit that you will receive updates in the future. I bought this rather than the book because updates sounded like a good idea and now I regret it. My issues are: 1) It lacks many features of an ebook reader like: Being able to change font size and background colour; being able to search; remembering what page you're on if you restart your device; being able to view the same content on Android and IOS and other devices from one purchase. 2) There is no mechanism to be notified about what is updated, and there is so much content here that it will take me years to read through it, so I don't think the updates are actually of use to me. 3) I've since found out that some ebook sellers allow authors to release free updates. I wish CVI had taken this approach. Overall, I wish I'd bought the paper book for two thirds of the cost.
Train to Sing in Tune – Vocal Exercise, Warm-Up, Ear Training and Singing Lesson