Reminds me of Japanese: The Spoken Language, which is what I used to learn Japanese. It's quite challenging at first but I can't think of a better way for an adult to learn the language well.
I am going to knock this because I used it. Problem: the written part of Japanese. You read this book and learn how to talk a bit, take a plane to Japan, then bam - surrounded by the visually amazing, but daunting Kanji. The Jorden school of thought totally disregards the written and focuses on the spoken. That is fine, but the wrong path to real Japanese fluency. The best way to start learning Japanese is to get int…
I do agree that people who use this approach are behind others in reading / writing performance. Indeed, it took me awhile to catch up. But fortunately this is something you can pick up on your own fairly well.
On the flip side, to be brutally honest, 99% of the people (that I've met anyway) who come through programs that focus on reading / writing sound horrible when they speak. They tend to suck at grammar, their intonation is all wrong and have a very hard time creating complex sentences. It could just be the sampling that I've interacted with but I can always tell the difference immediately between a JSL student and someone who focused on reading / writing.
Why is this important? It depends on your job / life but I personally spend my most important moments interacting with people via speech, not text. I'd much rather create a strong impression in person up front. It makes all the difference.