I read this book because I was looking for a carefully researched, reasonably authoritative history of the Mossad. It soon became clear to me that this isn't necessarily it.
There's no doubt that Gordon Thomas has met (and perhaps been rather too impressed by) some of the major players involved. That alone makes me sceptical about how truthful his book is. If Mossad is as awesomely powerful and accurate as he seems to think they are, surely they would never let a book like this get into print.
The evidence for the prosecution largely resides in Thomas' relentlessly gee-whiz, ain't-it-cool style. He seems to be endlessly impressed by Mossad's brilliance, and can't even recognise a blatantly bungled operation as such even when it's totally obvious, as in the idiotic attempt to assassinate Khalid Meshal in 1997. Even this fiasco can partly be blamed on the stupidity and impatience of then-Prime Minister Benyamin Netanyahu, but Thomas is so seduced by the myth of Israeli purity of arms and infinite competence that he can't even see blatant incompetence when it's staring him in the face.
Elsewhere, Thomas makes many simple errors. It should be obvious by now that I am no fan of the Mossad, but even so I think it's only fair to be honest about their achievements. Contrary to what Thomas says on p.80, Mahmoud Hamshari did not have his head 'blown off' by a bomb planted in his telephone; he was severely and, as it turned out, fatally wounded. Likewise, Pope John Paul I's name was not 'Albino Luciano' (Pope Lucky, anyone?) but Albino Luciani. Gerald Bull's design for a supergun was not '.45 calibre', which would have been a very narrow gun indeed, but called the GC-45 - and it was 155mm in calibre.
It can be argued that these are nitpicking complaints, but Thomas' book is unstructured, severely lacking in notes and generally far too impressed by Mossad and its world-view to be convincing to anyone who doesn't share that world-view.
The book carries endorsements by Meir Amit and Ari Ben-Menashe, respectively a former head of Mossad and one of its most brilliant agents. The world of secret services being what it is, that should be enough to make most wary readers doubt the veracity of everything Thomas has to say. He strikes me as being far too in love with these guys to be able to tell when they're feeding him a line.