Duolingo is great to get your feet wet, but its teaching model doesn't scale past A2/B1 levels (and in speaking/listening even less so). This valuation is enormous for a company that's virtually been for 10 years in losses. So far Duolingo has made the experience more painful to free users to push them to pay, and yet hasn't managed to get out of the red. I think the main that most learners are from developing countr…
I was a paid user for some time. It's inexpensive and fun. I mostly paid to encourage them, and to be able to use it offline in the plane (it's a fun game). However, as most people, I haven't flown in a long time, so I cancelled it. I wonder what are the main types of paid users. Otherwise, when not paying, I use the web version, and never noticed any advertising.
When reviewing lessons you're already familiar with, you tend to spend more time watching ads and Plus reminders than actually learning anything.