I was learning Brazilian Portuguese using Pimsleur CDs while commuting. I thought it reasonably good, though without feedback it was clear my pronunciation was not that good.
I’m now using Duolingo to study Yiddish. It seems pretty good - the drawback is that I’m not spending enough time with it, but that’s on me and not Duolingo.
Bottom line - I think both Pimsleur and Duolingo are of value.
I took a year of Mandarin at Pitt last year and I’m going to continue taking it. No memory techniques involved (besides flashcards) but the method they use focuses on immersion. I spent 6 hours in class each week, plus doing about 10 hours of studying a week. I think when your goal is speaking fluently, this makes the most sense (though having a private tutor would be even more ideal). It is hard for me to understand how using the method of loci can help you learn a language conversationally. If you just want to read in a language, I can see how loci can help. Maybe Josh can give me insight into using the art of memory?
Have you tried experimenting with a memory town? I’m not sure how Mandarin is organized.
I haven’t tried to learn any languages in a long time, but I was recently editing the Hebrew words on Memory League and ended up signing up for a Hebrew class. (My level is very basic.) I use mnemonic images for words, trying to place them in locations, but I don’t put them in a memory palace. I use the method of loci for some of the grammar. I’m going to add a memory town once I understand the logic of the verbs better.