Unpopular opinion: I don't find them useful. They are enormously addictive, which isn't a bad thing if this leads to good results. What I found is that they create the illusion of results and false achievements ("Yay! You're intermediate now!") when in fact, they don't get you significantly nearer to achieving your goal of understanding and speaking the target language. That was my experience at least.

I used one popular app daily during my commute when I was first attempting to learn Russian. By the end of the course/challenge (I cannot remember what it's called), I had convinced myself I was at a lower-intermediate level and the app seemed to confirm this. What a joke! I couldn't understand even simple Russian videos and songs, couldn't read at anywhere near a normal pace, and when I had my first conversation with a teacher, I could barely understand or say a word.

It's mostly a grammar-translation approach (so, nothing revolutionary or firmly grounded in anything evidence-based) and one in which you select or re-arrange words, so the results aren't surprising. I don't recommend them. In my opinion, the time would be better spent getting a solid foundation so that you can read and understand simple sentences in the same time frame. Ideally, whichever approach you use should include an evaluation of your ability to understand gradually more challenging sentences and communicate in a way that the people listening can understand.

@človek

We meet again! I think that these apps and their assurance that you have almost everything you need to know, despite being at a low beginner level, if that, in fact slow down people who have not yet learned many languages. They spend precious time on a game and think they are further along than they are. It can be very difficult to let go of the idea of oneself as already advanced or even intermediate. Yet, that's what is necessary if one is to progress. The earlier it happens, the better. That first conversation can be so crushing for some people who are invested in the image of themselves as already proficient in a second language that they might give up. It's too threatening to the perception of having arrived.

@Marcelo

Gamification has been a buzzword in education for several years now. I understand the idea, but if the principles aren't in place, it becomes yet another dressed-up distraction.

Great points all, @Guyomar ...

And I find your opinion well-founded and well presented ;)

After two years of constant use of the aforementioned platform my language level in Spanish was still best described as A1 (using the levels the Goethe Institut applies, A1/A2/B1/B2/C1/C2 with C2 being full academic proficiency), yet the app happily assured me I was 96% along the way ... what a joke.

Personally, I think it depends on your goals. If you want to exercise your language skills, of gaining some new vocabulary, this is perfect for you. But if you really wanna achieve a conversational level or fluency, you should find a way of learning that works for you, because not everyone learns by the tradicional way and not everyone learn by the way you do. My conclusion is, find a way that you best learn something, try to find the best approach that works for you. This way you are not going to try fitting in somebody's approach, and you'll maybe find your own . Once you understand your way of learning, it will work with any language you are willing to learn.

Personally, I think Duolingo helped me to learn French from basic by myself even though it doesn't provide daily relevant words at the beginning. Duolingo provide fun learning for beginners, which is important to start learning new language. I also learned grammar only by looking at the pattern during the lesson, but I recommend everyone to search for other sources if you want to have significant improvement. I can't find any other language learning apps that as fun as duolingo, yet.