When preparing for trips to Sweden and Italy I've tried Duolingo, Rosetta Stone and Pimsleur. Pimsleur is the only one that worked for me. After about a week on DuoLingo I could say "my cat ate the window on your table". Rosetta Stone was not effective for me as it was emmersion and I would look at a picture and wonder what part of the content I was supposed to pay attention to. Us engineers are a PIA to teach.
Pimsleur, however, scratched the itch: I wanted to be able to start every conversation in the native language, be civil and courteous then admit that I did not speak their language well and did they or someone speak English. And I wanted to say "thank you VERY much" a lot. That's was Pimsleur's approach too. And their degree of new words and repeating of previously taught words was just right. For me there is some gap between taught and learned so repetition and reuse of words and phrases is needed. Pimsleur CDs were very effective for both svenska and l'italiano. I'll use them again when I learn German.