I think it is worse than flashcards because you usually use flashcards after a tutor who can give you some context around what you are learning. I found two big

I think it is worse than flashcards because you usually use flashcards after a tutor who can give you some context around what you are learning. I found two big problems with Duo: 1) You are not given any input as to why or how e.g. German words are conjugated, not just verbs but adjectives as well, you are just expected to learn them. If you don't know what gender is, as an English speaker, then trying to learn der, das and die won't make any sense whereas if they said, "German uses different words for 'the' so make sure you learn the article with the word to remember which it is", it would be more useful. 2) The insistence on being text-based makes learning things like Japanese especially hard. Many people only want to speak and understand a language so forcing them to also learn an alphabet just makes it even harder, especially since in Japan, you won't see everything in Hirigana anyway! If you want to help with pronunciation then you could use a pinyin to do so. I also thought it was quite funny that the premium version gave you tutoring, in which case, I might as well attend a college class?