I am an I Ching user for 40 years. At first I was skeptical of this app, but, what the hell, its only $5??
What a surprise! Its really clever and very helpful. It includes 4 commentaries.
But something was missing. I am very familiar with the Richard Wilhelm version and the R.L. Wing version. After a couple of days
I discovered that these commentaries are available as apps within the app. (look under Store).
They cost $5 & $7 respectively. Well worth it considering the book costs.
So with these 2 commentaries I feel complete.
Dorvalian about Yi Jing, v2.3.1