In their introduction to Grey Wolf: The Escape of Adolf Hitler, the authors elaborate that their project initially began as a conspiracy theory program for television. It would have been best had it remained that way, as a thirty minute television special would be far more appropriate for the amount of material on Hitler's survival. For a book about Adolf Hitler, Grey Wolf is short on its subject matter. Copious amounts of ink are devoted to tangential, or outright irrelevant happenings of WWII. The authors could have simply stated the Germans stole large quantities of artwork and used their sale to finance their ventures in the aftermath of the war. Instead, there is usually a very exact listing the number stolen, and from which Rothschild's estate. Similarly, the recounting of the V1 rocket program, and the Monuments Men, are recounted at undue length and feel as if they're merely padding.
Aside from this problem, the case presented for Hitler's escape is merely plausible. Certain people claim to have seen him, and spent time with him. The logistics were in place, and the authors do a good enough job of setting them down. It could have happened. But then again, perhaps not. Hitler seriously considered suicide after the suicide of Geli Raubal and in the aftermath of the Beer Hall Putsch; thus, it seems more likely that he would have committed suicide during the fall of Berlin than to have absconded to Argentina.
There is also the problem of the prime mover in the whole affair, Martin Bormann. The circumstances of his death, and whether the corpse discovered is really his, are up to debate. The authors do not deal with this whatsoever.
Grey Wolf, if you decide to purchase it, is best skimmed through in large parts, until the writing that actually deals with the escape of Adolf Hitler is presented. A sincere commendation I will make is that parts which the authors consider pure conjecture are presented in italics. Those who are interested in the subject would be better off perusing the publicly available US goverment files on the matter and coming to their own conclusions.