The auido in Vietnamese is lacking
I am taking multiple courses on this site and so far, so good. The only issue I have is that the Vietnamese seems to have much less spoken parts (as in the words are said to me) parts than any of the other languages I am trying to learn. Personally, I think it is much harder to learn the language without this.
There are many problems with the course in addition to audio. As far as I know, only one volunteer involved in cleaning up translations. It needs more volunteers. Wait until you get more advanced lessons translating spoken Vietnamese to English. There are about three sentences I know of where the speaker omits a word so if you transcribe it perfectly you will be marked wrong.