I love the SVFF system and resources
The SVFF system and courses offer a wealth of material to dive into. I'm an absolute beginner with no real background in the language and love the way they've structured the lessons and how they build on one another.
It may not work for everyone, but starting first by learning pronunciations, tones, and reading, has built a strong foundation that's allowed me to see or even hear a word (in a lesson or in real life with native speakers and business names/menus) and be able to break it down prior to even knowing the meaning. The actual website and textbook has a lot of tools for bettering your understanding, listening, and pronunciation. I actually think that when you look at the "textbook" page it's easy to undervalue what you're seeing, but the top navigation bar alone holds 3 or 4 resources for vocabulary building along with proper pronunciations. The left side navigation bar then has another 2 or 3 resources, as does the right side bar, with the actual lesson content making up with center of the page. So that single lesson page has a ton of value packed into it with audio, video, dictionaries, pictographic explanations, crosswords (among other language useful games), and the actual lesson itself.
My teacher is Miss Thảo Tâm (Cô Thảo Tâm) and she has extreme levels of patience because I slaughter Vietnamese pronunciations constantly. She's great in personalizing the lessons to what I need to work on, answering questions that I have that are ancillary to the lesson, explaining the "why" of particular language usage, and not letting me be lazy. She's also been diligent in explaining the differences between the pronunciations when reading (reading pronunciations can differ from spoken), and Northern vs Southern dialects (I'm learning the Southern dialect but still need to be aware of Northern differences). I'm not sure if all the teachers are as well prepared and insightful, but it goes a long way to helping me reach my language goals. There have even been times when I'm with relatives and have messaged her on Skype to help me with being able to say a word or phrase.
I speak 2 other languages (Japanese and some basic Spanish), but Vietnamese is a completely different ballgame and so far I'm definitely seeing great progress via SVFF and it's noticeable when interacting with friends and family. I was skeptical about not having an in-person lesson (since I'm not located in Vietnam), but so far so good.