I haven't encountered any to be honest. Can you link to one as an example?
https://news.ycombinator.com/item?id=45411915
IMO, Duolingo. Makes claims about language learning that I found to substantially exceed what was delivered.
https://news.ycombinator.com/item?id=45411915
IMO, Duolingo. Makes claims about language learning that I found to substantially exceed what was delivered.