I adore this app because it is simple to use, lots of information, fun to use and test your knowledge, great sounds, great animations, pleasant colors, pleasant layout, easy to follow, very handy, and the cost is very reasonable. I am not a musician, but I have had music in grammar school and high school. I love music. I have studied music theory on my own throughout my life. It's not easy to learn by yourself, and thankfully those studies in school gave me a start to learning on my own. I already have the other app, which is included in the Bundle, and I love that one as well. Both apps are wonderful to learn and have fun at the same time, which is important, because if you do not have fun while learning, it becomes a chore, which can bore you to pieces. I have a number of books that teach music theory which I found to be boring, and there is no sound in a book (unless it's an interactive ebook or something similar), so I had a difficult time trying to learn from books. That is why I find these two apps to be a great help to me. especially considering the cost. And if you cannot afford music lessons, then here's your answer. I have to give this app five stars. Great job, thanks!