I think it is alright. There are a lot of paywalls for this so you wont get the best experience unless you pay money. It never taught you any conjugations of words and not how to hold a conversation. It teaches you words instead of being able to speak it.
Duolingo is perfect for learning a new language because it incorporates all areas required to understand a language fully. The sections it provides that test the ability to write and listen as well as speak in the language make Duolingo much different than other language learning platforms.
Learning a language should be fun and Duolingo makes sure to follow that. Lessons build up as students progress in their new language. If students need additional help with a particular field in their language, Duolingo provides support options that educators can access for their students. Also, overall it is easy to navigate with little to no technical issues.