Mike Houlahan has read and reviewed the book and this can be read by following this link. Once on the page close the window and then hover over the image of the book and click to enlarge. His main point is that "the action drags terribly as Karam attempts to rack up more points against the Crown rather than inform or entertain the reader". Houlahan's conclusion is that the book will not lay the case to rest.
Peter Graham has also reviewed the book for the Listener. He is not nearly as charitable as Houlahan, arguing against many of Karam's contentions, including the 'trial by ambush' monicker: "The title Trial by Ambush is a strange choice, suggesting that the main focus is the defence being taken by surprise at the first trial. In my view, that complaint is pretty much unsustainable, for reasons I could easily explain if space permitted" and "Robin Bain had a full bladder at the time of his death and could not have walked around killing all these people without first relieving himself". Graham is very careful to keep his review from skirting into the realm of defamation by contending that "As an advocate in court, you are not allowed to lie or wilfully misrepresent or misquote the evidence, but you are free to emphasise heavily, even at length, those parts of the evidence that support your case and skate over, skirt around or ignore altogether – if you can get away with it – items of evidence that weaken it. As a defence lawyer, that is what you are paid to do. And it is what, it seems to me, Karam is doing in this book." He should know since he is an ex-lawyer. Graham is not pursuaded by Karam's arguments.
Update: Massey University reviewer, Hayley Locke has written an in depth and balanced review.