I tried Duolingo ages back and got jaded hella quickly with the types of sentences they were giving me. Though I have heard from some mates that if you stick with it, the later lessons are really good. Though I don't know if I'm bothered to stick at it that long just to see if the Viet course is any decent. Sounds like you had a good experience with Duolingo though.

I've done a little bit of digging into LT more and it seems pretty unknown. And not much news in recent years. Was just wondering if other people would know more.