Very intuitive to use, and well designed from an educational standpoint- Im just learning Hangul for fun, so perhaps someone learning for business or a more serious reason would want to pay for a more in-depth app. That being said, I have learned several languages through formal and am in the process of being certified as an English teacher, and I speaking from that background, the way the lessons were broken into small, manageable units with a quiz at the end of each was perfectly suited for those learning on their spare time, or as a hobby. The lessons followed a clear flow, and the
charts with native speakers pronouncing the sounds were very helpful. My only complaint was that the "reading" part seemed very abbreviated, with no exercises, and only a handful of examples.
Schönerboner about TenguGo Hangul, v4.5.450