I have a wonderful pen-pal (or email pal) in Germany, and I have had the luck to meet Peter twice while he was touring around the US with his wife, Nicole. My father's side of the family is almost completely German, and my ancestors came to the US between 1830-1857. Not surprisingly, the language was not passed down to my generation. Peter was kind enough to translate a legend from the Facebook page of Andernach, the hometown of my great-great-grandfather, Phillipus Zerwas, but I thought it would be interesting to learn some German on my own. I liked Mango in that it gave you basic phrases and a lot of repetition that reminded me of my first years of French in middle school. But I found that I am not retaining it without having an opportunity for constant use. I have, for years, wanted to take sign language, especially knowing that my son might have a genetic tendency for a hearing loss (luckily, he doesn't), but without an opportunity to practice my skills constantly, I have put my energies elsewhere.
I took five years of French in school. I got a 97 on the statewide exam (in 1984). But when I was at lunch with John and Chris the other day, I could only make out some words here and there of the conversation of the people speaking French at the next table. The rest of it was bleh blah di bluh bluh....I can read it much better than speak and hear it now that I am so far removed from actively learning it.
So am I going to be fluent in German using Mango? No, but it is a good place to start. You can get a feel for the language and then move on to more intensive instruction.