This textual commentary is designed to be used in conjunction with the United Bible Societies' (UBS) Greek New Testament 4th ed. and its greatest utility will be found within that scope of use. Nevertheless, there are uses for others, even non-greek readers; however, the utility will obviously be less as this book was not written with you in mind. The pupose of this commentary is best given through a quote from the book's introduction:
"Most commentaries on the Bible seek to explain the meaning of words, phrases, and ideas of the scriptural text in their nearer and wider context; a textual commentary, however, is concerned with the prior question, What is the original text of the passage? That such a question must be asked - and answered! - before one explains the meaning of the text arises from two circumstances: (a) none of the original documents of the Bible is extant today, and (b) the existing copies differ from one another."
The commentary is basically a verse-by-verse list of the all of the verse's identified by UBS as having variant readings in the Greek texts from which the 4th ed was compiled. Without such a tool we are left to look at the readings which were chosen, perhaps the variants which were provided, and guess why UBS made the decision that was made. Looking at variant readings in both English and Greek texts one has very little indication of what sort of weight which variant carries. So, the commentary is basically a verse-by-verse, variant-by-variant list of variant readings along with the determination made by UBS along with the the following categories regarding the certainty of the reading which has been chosen:
A: The text is certain
B: The text is almost certain
C: The committee had difficulty in deciding which variant reading to place in the text
Each decision is accompanied by a paragraph-form (often many paragraphs) explanation of why the committee's determination was made in the way it was making great use of major texts and transmission lines.
This commentary has proven very useful to me. In my opinion the introduction alone, explaining textual transmission and the issues at hand, is worth the purchase price alone, but once you purchase this commentary and realize its usefulness, it will likely become an oft-referred to member of your library.
The only thing keeping me from offering 5 stars to the book is that the only book with a thorough textual transmission introduction is Acts. This is extremely helpful and deals with issues which are only superficially, ignorantly, or inadequately dealt with in other commentaries. I am very greatful for the work of Metzger and UBS for writing it. However, I think that if an intro were available for the rest of the books, the commentary would be very well rounded. Nevertheless, the Textual Commentary on the Greek New Testament accomplishes its stated purposes very well and has proven extremely useful to me.