Duolingo review

Duolingo. I've been using it for a few months now. It's a good app (website and smartphone app). The best features, in my opinion, are the streak functionality (tracking how many days you have done some language learning) and the spaced repetition functionality (it has you go back and practice old stuff at spaced intervals of time). The things that I wish could be improved are the vocab taught. The first lessons are words like man and woman, boy and girl. Although it may be crazy easy grammar to learn "I am a man", I never see myself saying such a thing to a native speaker, nor have I ever done so in the past. I would love to learn vocab to help with practical speaking. That being said, I don't know if that is the purpose of duolingo. And maybe there is something about language pedagogy that linguists know that Duolingo is implementing. That's just my honest, simple opinion.