The app became way too Duolingo-fied. Sololearn used to be an app to learn how to code and use different coding languages in a fun way, now it's just a game with coding elements (just like Duolingo won't help you learn a longuage in an efficient way), you can't learn anything with their new courses, it's kind of braindead (you don't even need to read anything to get a good answer!) (which is weird because of the code coach at the end of the lessons that have been unlocked from premium), you might learn something with their older courses (but be careful, they will be changed at some point)
I do not recomment this app anymore.