There are a few reviews, by David Fuller and myself. The analysis runs very long, against hundreds of pages by Neumann. Stronger than any refutation is, I believe, the following. What was arguably the most important thesis of Neumann (that all the weak-beat ornaments in the Baroque era are to be played pre-beat) is considered fundamentally flawed by all the modern scholars I am aware of. Indeed, there is plentiful of well-documented evidence that (with just a handful of possible exceptions in some early baroque works), throughout the Baroque era and well into the middle of the 19th century all the trills and mordents were played on the beat (when not after the beat).