[user568439]

It's a good tool but it's not enough to learn a whole new language. As a user it helped me a lot to memorize new words and also to easily understand common sentences and expressions. For speaking and writing skills is much more limited and you would need a teacher and real-world practice.

But I used Duolingo + Anki for all the vocabulary stuff and then I could focus the paid lessons on grammar + writing + speaking to be more effective (and save time & money)