This book has raised a lot of controversy. In this review, let me answer a couple of basic questions:
What's in it? In A Different Jesus?,
Robert Millet, a leading Mormon scholar and apologist (though not one I ever had cause to address), provides what is, quite frankly, a sanitized advertisement for the doctrines, beliefs, and virtues of Mormonism. Think here Coke Newell's Latter Days, a work likewise seeking positive reputation for Mormonism, but also offering much that is not new.
From Millet we get, as with Newell, little in the way of acknowledgement of the exegetical problems associated with Mormon use of the Bible; expect a glossing over of serious problems with New World archaeology and Mormonism. Millet only assures us that "much work has gone forward"  on the subject, begs for more time, and suggests that objective evidence is not that important in the first place.
Do not expect many of the darker problems to be dealt with (e.g., Mountain Meadows), though surprisingly, a few of the trouble spots are dealt with (such as the Book of Abraham -- though to what quality extent, I am not informed enough to say).
On the other hand, unlike Newell, do not expect an emphasis on how badly Mormons were persecuted for their beliefs: Millet rather takes the approach of winsomeness. And do expect frank admissions of some of those doctrines of Mormonism that are shocking to mainstream sensibilites; though not the same ones that Newell covered.
The content itself is informative -- each chapter discusses particular Mormon beliefs in great detail. Millet cleverly (for his position) makes use of mainstream Christian writers often -- particularly C. S. Lewis (even using the trilemma argument as a point; 35) -- but also uses a source or two of questionable worth (eg, David Bercot).
His explanations are sometimes persuasive or reasonable, but at other times are not. The long defense of Joseph Smith's declarations about the abominable nature of Christendom in his day, for example, fail to obscure just how strong those statements were -- and in turn, how in fact inconsistent Smith was in his later approach. The apology that says, "well, the rest of Christendom is not so bad after all" simply does not convince. Smith's production of a new "translation" of the Bible itself, among other things, belies such a moderating explanation; and the quite significant difference in doctrine says even more.
It also rather speaks for itself that Millet is aware of such things as the interprtetation of 1 Cor. 15:29 by the most recent scholarship (White, DeMaris) and doesn't interact with them in terms of how they have demonstrated that the Mormon interpretation in error.
Of great use is the last section in which Millet answers "recurring questions". Some of these should be taken with a grain of salt; Millet's plea, for example, that "events of the Old and New Testaments" have only been corroborated by archaeology in recent years, as a plea for more patience concerning Book of Mormon archaeology, is nullified by the fact that both books have had the same amount of time to be verified by the professional use of archaeology, which has only existed for a few decades. It is not surprising that Millet ends up stressing far more the subjective experience of the reader of the BoM than the problems of its authenticity.
What's the controversy?
It comes mainly from two issues. The first is that this book is put out by Eerdmans -- a reputable mainstream Christian publisher -- and is apparently meant to be sold in Christian bookstores. Admittedly for someone in my position this is hard to be upset about personally. A thousand works by Millet could be in the Christian bookstore and none would be convincing to me, barring a bombshell Mormon apologetics does not possess.
It is no argument that such a work is not needed, and we could go to a Mormon bookstore; an everyday Christian too interested in the latest fiction isn't even going to know where their nearest LDS bookstore is, much less what or where their books are.
"Know thy adversary" remains a wise course, and letting the adversary speak for himself is part of the process of critical evaluation that we so desperately need to keep ourselves spiritually fit.
On the other hand, I can understand why some may worry that the average Christian will get hold of this and suddenly think Mormonism deserves a legitimacy that, academically and factually, it does not deserve. Millet will lure in far more sympathy than he ought to. On the other hand, we already have Christian bookstores selling material by people with questionable doctrines, so it's hardly as though we have not had our territory invaded already. I think in this case it is better to blame our churches, with their self-centered focus, for not making it so that we can indeed walk into a Christian bookstore, see a work by Millet or the like that would indeed be of value for the serious student, and worry that someone will convert to Mormonism because of it.
I am reminded of a former pastor of mine who appreciated my book on Mormonism, because, he said, many of his Baptist parishoners believed that God had a human body -- though they had no idea Mormons also believed that very thing. I don't blame Eerdmans as much as some might -- the problem is much larger than Eerdmans, and their production of this book is merely a symptom of the problem, and one that will exacerabte the symptoms, not the problem itself.
The second thing is a little more troublesome. Richard Mouw of Fuller Theological Seminary closes the book stating that, "I think that an open-minded Christian reader of this book will sense that Bob Millet is in fact trusting in the Jesus of the Bible for his salvation. That is certainly my sense."
It is? Perhaps next we can also welcome in the JWs with their Arian Jesus? Mouw has tried in other venues to note recent approaches stressing that the OT teaches monolatry, not monotheism; but that is a diversion, since the issue is the fundamental identity and nature of YHWH -- and that is something that has been specifically regarded as non-negotiable, from the time of the Gnostics up through Nicea and to the present day. Mouw has assuredly mis-stepped here -- arguably, a Mormon could be saved, as I have said, not because of the doctrines of their church, but in spite of them (after all, are those Baptist parishoners headed to eternal perdition because they believe, in ignorance, that God had a body? -- and how many out there actually understand the Trinity, anyway?).
But Millet is educated enough to know the difference, and also educated enough to know to not tackle the issue head-on in this book, lest it refute his purpose. Mouw would be better off doing as we would do -- neither condemning nor affirming a person's personal salvation, but withholding soteriological judgment even as the truth is presented and the errors are corrected.
So in conclusion, is this book of use? Yes, and that's why we give it a positive rating, as we did once to Hopkins' Biblical Mormonism -- not for accuracy in terms of religious truth, but for being something an apologist can educate himself with.
And is it a threat? To me, and to informed Christians, no -- but for the average Christian to whom we may think it is, we have more ourselves to blame that Millet or Eerdmans in particular.