Good at first, meh after a while
German - The voices are inconsistent and sometimes pronounce things incorrectly. Also voice recognition is hit or miss. It will sometimes correctly detect what I said and then change the words to something wrong immediately when I hit "check", then says I am wrong. Finally, Duolingo will sometimes introduce variations of a new word and not explain it at all (Dein, deine).
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Duolingo Learn Many Languages for Free, v5.1.6