"Duolingos user interface and gamification might have become more annoying, but the real problem is that this approach to language learning is incredibly inefficient at best and probably does not work at all. It just feels productive."

^This. Spot on. I was fooled by Duolingo and wasted way too much time on it before I caught on and deleted everything Duolingo from all my devices. Now I'm finally making actual progress in my language learning. I never used Duolingo alone, of course, but the effort I spent there impacted my learning negatively and made everything ineffective.

Stay away from Duolingo. It's fool's gold.