Im very impressed with this app. I downloaded it to start learning Esperanto and ended up brushing up on the other languages as well. I study 9 languages and I find this app a good way to practice when you have waisted down time. I would love to see more languages added like Mandarin, Hindi, and Thai. Its hard to believe this is a free app. Its much better then many of the paid apps out there.
mkimmey about Duolingo Learn Many Languages for Free, v5.0.14