I think Duolingo offers a wonderful service, and I really enjoyed it while I was using it. Currently, my only feedback for the team (if they're reading this) is that it might be a great idea to partner with popular exchange programs to notify highly-active users of opportunities to live in another country for a while to hone their skills even more!

For example, I participated in Explore, a Canadian immersion program that offers a chance to live in Québec for five weeks and really improve your French by speaking it day-in and day-out. Targeting such programs to their users could be a great value add.

I've used Duolingo in the web and in an iPhone, and speaking as a developer it's depressing to see how good and polished is this app. I wish I had their eye to nail down a perfect UI/UX.

I installed the Android app right now, and seems to be even better than their iPhone app (you can type directly the translations instead of choosing between a closed set of words). It's a fantastic app, highly recommended to learn a new language.

It will be great if they could add a way to chat with other users like in verbling.

I'll be all over this when it's compatible with my Nexus 7 :)

Great! Been waiting for this one.

What is so special about this application compared to other ones with the same purpose?

It's free, and also by learning with Duolingo you're helping translate the web. http://en.wikipedia.org/wiki/Duolingo

Thanks for the real answer to real question. After trying it for 5 minutes I got so hooked up that now I spend almost an hour daily practicing and improving my German skills.

The site and application are really important missing step between a language beginner which doesn't know the language enough to be able to improve it organically by random reading and conversation, and an intermediate speaker that can go forward on its own.

I would really recommend this tool, especially in combination with real language course. The app is great, but the site is still better, since the some things are missing from the app. I hope the app will catch up to the site usefulness, since it is so much easier to use when commuting.