I've been using Duolingo about daily for over 200 days. I've been sad to see more ads forced and some design anti-patterns added.
Example-
Before: When finishing a lesson on Android, it showed an ad and had a button at the bottom that said something like "Ok, close"
After: Same button at the end of the ad now says "Go Ad-Free for $9.99 a month". They added a tiny "x" in the top corner to close the ad. By instinct, I keep clicking the "Go ad-free" button, but when you enter the ad purchase screen and try to exit, it says "Are you sure you want to quit? All progress will be lost." Clicking "exit" implies that your lesson you just completed will not count, but fortunately this does not happen.
Changes like this, plus stale content that doesn't get very advanced, have made me go from a promoter to a detractor.
I thought it was interesting that duolingo is seeking an Ad sales director. It seems they have completely given up on translation sales, and aren't pursuing sales of educational services, which apparently leaves them looking to add advertisement to their product.
Example-
Before: When finishing a lesson on Android, it showed an ad and had a button at the bottom that said something like "Ok, close"
After: Same button at the end of the ad now says "Go Ad-Free for $9.99 a month". They added a tiny "x" in the top corner to close the ad. By instinct, I keep clicking the "Go ad-free" button, but when you enter the ad purchase screen and try to exit, it says "Are you sure you want to quit? All progress will be lost." Clicking "exit" implies that your lesson you just completed will not count, but fortunately this does not happen.
Changes like this, plus stale content that doesn't get very advanced, have made me go from a promoter to a detractor.