It is virtually unanimous among those involved in biblical studies that Gordon Fee's NICNT volume is the best commentary written on 1 Corinthians or, for that matter, perhaps on any book. I will whole heartedly agree with that statement. This commentary by Thiselton is not a competitor but a complement to Fee's work. The NICNT volume is based on the NIV, with corrections made by Fee where appropriate. Comments on the Greek text are minimal and usually only found in the footnotes. Fee's comments are clear and concise, even if a bit underdeveloped for the needs of scholars and Greek students. Perhaps the best feature of Fee's volume is his wonderful introductions and summaries found at the opening and closing of each section of the book. This is especially important when discussing an epistle and conveys Fee's understanding that, despite the proliferation of word studies and word-by-word commentaries, words can only be understood in light of their entire context. Fee does all of these things wonderfully, and even includes helpful insights into modern application and contextualization.
I have included all of this about Fee, so that the work of Thiselton can be seen for the gem that it is. This volume is massive (almost one-hundred pages devoted to each chapter). For some, this is a problem. However, as one who as actually read the commentary (many reviewers have only read a few pages of the book they review), the bulk is absolutely necessary. In the preface Thiselton says that it was his intention to answer every question a responsible scholar might bring to the text. As he says, "I am keenly aware of the sense of disappointment so often experienced when readers take up a substantial, scholarly commentary only to find that in the end it has failed to address precisely the questions to which they are seeking some kind of answer" (xvi). If you have every experienced this frustration, you won't find it here.
Thiselton is a Greek scholar, an accomplished linguist, philosopher and theologian. This background makes this the most thorough commentaries I have ever read. Having been through the entire commentary, I can say, there is no question that he does not address. This is not to say that I agree with all of his solutions, but at least he attempts an answer. He pays close attention to the Greek text, addressing text critical issues where appropriate as well as syntactical issues.. He gives sociological and rhetorical criticism sufficient weight, without allowing these more subjective disciplines to run away with the clear sense of the text. He carefully traces the flow of argument in the epistle, and like Fee, introduces and summarizes every major section of the letter so as to keep the entire argument in focus as the commentary progresses. He offers many special studies into particular sticking points of the letter--the point of rhetoric in 1:10-4:21, the possible source of the divisions, the meaning of sophhia and teleios, divorce, Paul's use of the OT and MUCH more. As I said, every responsible question is addressed. As a counterpart to Fee's not to present day application, Thiselton includes a substantial section on the history of interpretation and wirkungsgeschichte after each chapter.
So, is this commentary worth the money? First ask, what are your needs? This commentary, despite the claims of the NIGTC editors, is not altogether suited for those just beginning Greek student, and certainly not for those unfamiliar with the language. These two groups could still utilize certain sections, but would miss many of Thiselton's careful points. If, though, you are skilled in Greek and fed up with commentaries that go on and on about simple points and never address the challenges of the text, this is for you.