I've now seen this new book at my local library (which was given a pro
bono copy by its authors - thank you!). And I've also seen the full
complement of the installments in TG by which this material was
originally published. The content and format of the book is
substantially the same as the TG articles, but as mentioned it now
incorporates many additions and corrections. Most of these additions
and corrections were probably published in TG also, but now they
appear in the proper places in the ancestry, rather than showing up
haphazardly perhaps many installments later.
It's somewhat misleading to label this as "self-published", as the
material has certainly been subjected, in its originally published
form, to the rigorous editing and peer review customary for a journal
such as TG. Of course, in a work of this magnitude there will always
be details and interpretations with which one may take issue and
disagree. But on the whole this is certainly a reputable and
scholarly work, and one which will be valuable for many of us.
I've always questioned why a work such as this was originally
published in the way it was: essentially as "filler" articles in TG,
and spread in chunks over a very long time. This new version is
certainly a long-awaited improvement.