I searched the subreddit and James Douglass' book was not mentioned. I found the book featuring a surprising amount of evidence from a wide variety of people. Is there any reputable, scientific review of the book? Beyond "if it's calls it a conspiracy it must be lunacy".
In all the journals carried by JSTOR.org, the only scholarly journal that reviewed this book was the now-defunct Human Rights Quarterly, formerly published by Johns Hopkins Press. The review was by David Lempert, who is an anthropologist and not a historian. Most of the half of the brief review that was devoted to this book treated it from a standpoint of comparative social anthropology; the treatment of the author's forensic case was, at least in my opinion, superficial; you can, of course, read it for yourself and decide.
Apparently no historian or other scholar bothered to review it in any of the many scholarly publications indexed by JSTOR.
The publisher did not seem to be able to drum up many historians to blurb it, either; the blurbs are mainly by such "notables" as Martin Sheen, Yoko Ono, and (yes) conspiracy theorist Mark Lane. The one historian I could find among them was Gerald McKnight of Hood College, who was already a well-known critic of the Warren Commission report.