The latest release was on Mar 27, 2019 and Duolingo was downloaded and installed by over 100M users. Users rated the app 4.7 on Google Play. Some in-app purchases and advertisements are included into this application.
The tool is very popular among Samsung and LG users.
As users see it, you can notice such pluses of Duolingo as an easy-to-use interface, useful features and great support. From the users' point of view, you can find grammatical errors and ads after every level among the drawbacks of the app.