I must confess I debated to buy this because of the price and massive work that it is. It is going to be somewhat expensive to get all four volumes. However, I did invest in it because I am writing on Acts. As I am working through this volume, I observe:
(1) Keener is a serious and superlative scholar of the highest rank.
(2) It is a massive and detailed work. It is not a book for one who does not have some academic training. The depth and width of research numbs the mind. Commentaries come in different levels and are written for different audiences. It is clearly he is writing to an academic audience. It is one of the most academic works I have seen in some time.
(3) His approach is social-historical more than exegetical. The term exegetical is almost a misnomer, which he seems to admit (p.6). He certainly emphasizes social-historical, rhetorical and cultural connections of Acts over grammatical and lexical details. This is an important to know in considering this work.
(4) This surely will be the most comprehensive documented work on Acts to date.
In this massive work over 60% of this volume takes up introducing the book of Acts. The introduction is detailed, comprehensive and extensive, leaving hardly a stone un-turned. He gives all sides of major introductory issues, and completely document (many of the pages are filled half way with footnotes). I found much of the material as interesting. The parts of the introduction that I found helpful are on Paul and Acts, and the dating of Acts (although his conclusion is not the same as mine). However, the introduction may be too academic for many.
The heart of the work is the commentary. I find it very worthwhile. He takes a little different approach in that he centers his comments on verses by subject, rather than phrase by phrase. For example in Acts 1:9-11 his breakdown is:
Signs of Glory: Cloud, angels, Heaven and Return (1:9-11)
The Cloud (1:9)
The Angels (1:10)
Returning the Same Way He Left (1:11)
His comments are helpful and insightful. He has charts throughout his commentary. Along with a number of Excursus scattered throughout the commentary. His comments are loaded with background and thought in the first century. He aims to bring out the meaning and thinking of the original readers. In these areas he is unsurpassed. He is fair in the consideration and presentation of other views. There are others that are stronger in grammatical and lexical details (i.e. Schnabel, Peterson). However, he excels in his social-historical approach. He is reader friendly. Interestingly there is no printed index, but is on a CD that comes with the book, which I find cumbersome in using. There is no quick way to look things up. But again it is another 400 pages.
Overall, this is a top ranked commentary which will last the test of time. It may well become the best academic work on Acts and may be overwhelming for average readers or Pastor. It will become a necessity to use for any academic work and research. I urge caution before you decide to buy. I am glad I decided to invest in this work.