Im really enjoying this app, it truly does help you to learn rather than memorizing words and forgetting them the next day.
I wish there were more Asian languages as I am also trying to learn Korean.
My only suggestions are one, to have the option to reintroduce new words. When you start a new lesson, there are little pop ups that give you a little lesson on what the words mean. When you retake the same lesson, that pop up goes away. Second, it would be nice to have some sort of short cut to go back to. Say you get some words confused but you dont want to go back to the entire lesson to learn it, but be able to write it down in some notes and have the option to click on that during lessons to refer to. I hope that makes sense, I think that would be really useful though.
ericaewen about Duolingo Learn Many Languages for Free, v5.0.14