Some of this book's strengths are felt immediately once the reality that this little 220 page book is an exegetical force to be reckoned with (granted the print was small). First, much of it interacted not only with English writers but also German scholarship as well. This is only fitting and expected since Piper did his doctorate in Germany. But this exposure beyond American Evangelicalism is always good and extremely important. Piper also demonstrated various views and fairly presented them to the reader. I am able to say "fairly" (as in justly or accurately) because I used to hold to the view he was arguing against. He spent pages demonstrating the opposing views points and arguments. They even seemed convincing, that is until he destroyed them with his own points and arguments.
Every strength has its weaknesses, however. Piper's book is no different. Although it was central to his argument and established what the "righteousness of God" is in Romans, chapters 6-8 take a detour to build a case for his meaning of the phrase "righteousness of God." This was necessary to establish his point, but it did seem a bit taxing at times. It gave the book a sense of discontinuity that I felt would have strengthened his view.
Perhaps another weakness (or this could simply be my mistake) is that I was expecting a more "lay-level" explanation of Romans 9:1-23. Instead, what I got was a fantastic exposition of the Greek text. Piper didn't even supply translation or transliteration most of the time. So for those whose Greek (and Hebrew at times) needs improvement, it is challenging. This in turn limits the range of audience for which this book will be useful. Could someone with no knowledge of Greek and Hebrew read this? Yes, but it would be very difficult.
Lastly, Piper's conclusions are not real popular; at least they are not popular where I'm from. But I am glad he was willing to demonstrate and undergird them with solid exegetical support. The basic premise is that Romans 9 is dealing with individual election unto salvation. If that is the case, then what should we do with phrases like the following:
"I will have mercy on whom I have mercy, and I will have compassion on whom I have compassion,"
"So then he has mercy on whomever he wills, and he hardens whomever he wills,"
"Has the potter no right over the clay, to make out of the same lump one vessel for honorable use and another for dishonorable use,"
"What if God, desiring to show his wrath and to make known his power, has endured with much patience vessels of wrath prepared for destruction"?
Piper advocates reprobation also known as the unfortunately titled doctrine of "double predestination." This view sees God as the ultimate sovereign power of the universe. And yes, he creates some for honor and some for destruction. I would have liked Piper to develop that a bit more, but he mainly just cites Daniel Fuller who basically says that this is not unrighteous for God to do since the only way to express his great mercy is for people to see and desire it out of his wrath. This gives the word "grace" an entirely new meaning.
I hope for our sake that Piper, with his upcoming transition from the pastoral ministry to a teaching/writing ministry, will be commissioned by a publisher to write an entire commentary on Romans that will match the intensity and depth that The Justification of God reached (a commentary would also update this now almost 30-year-old book). This one was fantastic – 2 thumbs way up. It has a limited readership, but its usefulness for the study of Romans 9 cannot be denied.