At one point it was gamification to tie the reward center of your brain into continuing to train using the app. Now it seems that it's half that or half https://en.wikipedia.org/wiki/Dark_pattern to get you to pay to keep that reward system going.
Personally, my interest in language learning comes and goes. Doing the minimum to maintain a streak prevents me from forgetting too much before my interest returns.
Donde, está, la biblioteca. Me llamo T-Bone La araña discoteca. Discoteca, muñeca, La biblioteca Está en bigotes grandes, el perro, manteca. Manteca, bigotes, gigante, pequeño, la cabeza es nieve, cerveza es bueno. Buenos dias, me gusta papas frĂas, los bigotes de la cabra Es Cameron Diaz.
Having heard very mixed things about Duolingo's actual usefulness, does your wife speak or write well in any of the languages she's used the app to learn?
My friend learn japanese and able to speak fluently after using the app. Though she does have japanese customer from time to time that she can test it with some of them.