Something that bothers me both about Duolingo and Rosetta Stone (and similar apps...) is that they don't let you fail enough. What I mean is - when you were first learning your native language, you probably mispronounced lots of things and didn't understand the grammar. But you kept going, learning as you went. Duolingo et al. want you to get the pronunciation of things correct before they will let you go on to the n…
Most people manage to speak their native language just fine but very few speak it anywhere near perfectly.
Obviously, you need to learn the basics of grammar in order to construct a sentence that sounds more or less right but I'm not sure Duolingo can even do this with any degree of success.