I started on Duolingo about six months ago.
The thing is, I was doing great in the first couple lessons, but then I suddenly hit a HARD lesson. It passes you through the lessons. But as I recall I hit the lesson which was very difficult, and it sort of took the wind out of my sails.
May try again, but that was my experience anyway. YMMV.
Toi thich Duolingo nhieu lam! Khi nao ban gap mot bi ho thi hi phai van lam toi am dung. Duolingo khong la mot chien dau.