I will give you my take on his method below. As my anti -Vaughan bias is fairly evident, I refer you to the following pages so that you can make up your own mind:
http://www.ugr.es/~portalin/articulos/PL_numero19/8%20Betsabe.pdf
http://materialesparaingles.blogspot.com.es/2015/08/translation-booklet-c-o-folletos.html
http://materialesparaingles.blogspot.com.es/2015/08/v-systems-students-manual-complete.html#more
My Take on the Vaughan Method
The Vaughan Method is having huge success in Spain. It is a mixture of audiolingualism-via the highly controlled structural drills that are the mainstay of his standard classes- , contrastive analysis, to make Spanish learners aware of typical mistakes, and the memorization of lists of phrases, alongside their Spanish translations.
The contrastive analysis bit is not badly done, in as much as it focuses on a number of key areas that are not always covered in textbooks. The phrase translation approach is less convincing for a number of reasons: as far as I know, the phrases are not based on any frequency lists ; moreover, the lists seem to be put together in a rather haphazard manner, combining in the same list semantically-linked phrases, and phrases which have no connection to each other. Some of the phrases are clearly useful while others are redolent of "My Tailor is Rich".
The Vaughan method makes little or no attempt to contextualize the language taught or enable learners to use it in personalized or creative ways. Grammar points are normally taught as discrete ítems, rather than as part of a system.
During immersion courses, the Vaughan method does include some speaking classes. However, in its standard version, there is little room for speaking, or any other macro skill in his classes, as most of the class time is taken up with the standard method, as described above. At Beginner's level, 80% of class time must focus on his method. This drops to 60% at Advanced level ,allowing for a bit more leeway.