I feel the same way about Duolingo. I used to be able to speak a moderate amount of German and let it lapse. I picked up Duolingo because it substituted for some other casual activity I might do on my phone (crossword, read hackernews, etc.) And learning some conversational German feels like a better use of time. However it is pretty basic. I know there are hundreds or thousands of units and spending 10 minutes a day probably won't get me very far. Still if I keep it up and take a trip to German I'll at least know some of the basics. I practice with my long-suffering family who has to listen to me say Mein sohn is sehr klug! and other stuff like that all the time.