I used it for a while for a couple of languages, then it brought in a punitive method called… I forget what, but it punished you for making too many mistakes. I uninstalled it immediately. I suspect they lost a lot of users that time - there was a storm of rage on the site's forums.

It was pretty good; it taught a fairly slangy, hip-with-the-kids version of the languages. (If you want to know the kind of Spanish, there are two ways to find out: 1) doeth it lithp on the esses (Spanish rather than South American) and 2) ask on the Duolingo Spanish forum. Or search; someone else has probably asked already.

What I do use and like is a site known as The Mixxer, or language-exchanges.org - using this, you put up a profile about yourself (as informative or otherwise as you like) and include what language(s) you speak as a native and what you'd like to learn. Then people who want your language and can offer the one(s) you want will contact you through the site.

I've spoken to lots of different people in my chosen language, using Skype; I'm currently down to speaking once a week to the same person, who's become a friend, and who's brought me or been brought by me out for meals on my visits to the country.

The great thing about this is that you get attuned to using language, and people using The Mixxer are generally fans of language in general, so people offer each other useful tips like "Don't watch a film using English subs, use same-language subtitles".