First the good: we constantly need to be reminded to humble ourselves and to listen more closely to others. The book is an excellent reminder to practice these virtues more frequently, and for that alone, it is worth the read. This book does a good job of addressing one side of the cultural hubris that American missionaries are prone to have. The book is not just for Americans, nor is it just for missionaries, but it seeks to address cross-cultural "servants;" however, American missionaries definitely fit the primary audience of the book.
Now for the bad: If this book had been written a generation ago, or even three generations ago, I would have applauded it as extremely necessary and timely. However, in this day and age, a book that emphasizes the subjective subtleties of culture seems a bit like it is preaching to the choir. I have lived overseas for over 8 years of my life and have spent time among a large number of different cultures. This doesn't make me an expert by any means, but I can say emphatically that I have yet to find a culture that is more worried about being offensive than American evangelicals are. I can't ever remember hearing Nigerians or Ethiopians or any number of people from other cultures talk about things like "sensitivity training" or "ethnocentricism." I find it slightly ironic that we Americans are so terrified of ethnocentrism, but we've failed to realize that this fear is itself a bit ethnocentric. We are so steeped in a culture where trigger warnings have to be announced that we have a hard time fathoming the emotional resilience of people like those in Niger--a place where almost every mother has lost a child. Perhaps Americans have a greater responsibility to be sensitive to the needs of others since they come from the most powerful nation (at the moment) in the world. But, as even the author alludes to, I think there is currently far more danger that Americans will float along with the current of relativism and dilute the truths of Scripture in sycretistic fashion as they try to elevate the practices of local cultures than that they will rigidly require local cultures to adopt American culture in order to be "Christian." I agree with one respected theologian who said: "The most important things are those things that are common to all men in all cultures." Amen. And honestly...what words have become more anathematized in today's American culture than "imperialism" and "colonialism"? If we err, we will certainly tend towards emphasizing the subjective in an attempt to right past wrongs.
Additionally, there were times when I just disagreed with the author. I think he creates a false dichotomy between power/glory and service. He also seems to create one between thinking you know the truth and humility. In the author's view, you either think you know the truth and therefore act like an obnoxious know-it-all, or you are humble and lowly, and therefore remind yourself constantly that you don't have the right answers and therefore need to learn. But what about the excluded middle? Is it impossible for someone to be knowledgeable but also humble? Self-assured but also eager to learn? These things are not intrinsically opposites, but the author seems to want to make them so.