Hi fellow japanese language learners! After testing duolingo as a more advanced (longer term learner), here are my impressions. I think it can be useful for some beginner users but probably not good to use it in isolation. The reason being is that a lot of the sentences are just unnatural and you will sound very much like a robot or ai talking if you directly use the sentences from duolingo. The plus side is that it is fun to use, the sound effects make it feel like you are playing a game and can be good if you are feeling down on motivation.
by biryaniv2