[dfwgator]

The Spanish and French and German Duolingo courses are the “official” courses and are way more comprehensive than the other languages they offer.

[Vigilanteman]

That is generally what I hear. Superb for the Latin based languages, OK for the Germanic languages (to which English belongs), not so great for most of the Asian languages.

Japanese is the only language (plus English) to which I can claim conversational fluency and basic reading ability. All three of my daughters are better than me, having grown up there and learned the language the easy way.