So I just finished Sullivan's book. I'll take back a few things that I said earlier. In the latter half of the book, he does challenge many of the theories as well as how the show and Lagina's have handled some things. He isn't disparaging but does at least share his own opinions on some matters. For example, he's quite down on Zena Halpern and states that he quickly learned that he should do more listening then trying to share his opinions while on the island. That being said, he doesn't challenge much of the Oak Island mystery itself. Like I said previously, he seems to just assume that the stone is real and had markings, that there were oak timbers every 10 feet etc.
The book is laid out with a pretty decent history of all of the previous attempts. Then covers primarily the Templar, Spanish, Free Mason and Petter theory. He spends less time on the less accepted theories but does cover many of them briefly. He spends most of his time on the Bacon theory including some weird delving in to alchemy which was somewhat interesting.
He then discusses for a chapter the "negative vibes" people get from the island including some recent encounters people have had including a psychic. Expressing himself that he has been creeped out by the island and recounts a story from Marty where he heard a loud shriek from the money pit area when he was alone there one evening.
Overall, it's a pretty short book that spends most of the time on variations of the Francis Bacon theory and has a pretty good history of what's happened on the island to date. Other than some "behind the scenes" look, it doesn't add anything new to the discussion and is just rehashes of the many things we've all heard before.
A small thing that bugged me and is indicative of my overall feeling that he didn't question much or add to the discussion is in the back of the book, he has a timeline and pictures of artifacts and people etc. For Samuel Ball, he uses the same "Memories of Liberia" artwork that the show used for many years. Which..is fine but you should at least put an asterisk by it and say "not an actual picture of Mr. Ball". I would love to see a book that is just facts and not filled with blind faith and re-use of previous renditions. That's how future historians are going to get confused and not know what was actually real or not.
Last example of why I didn't like his style or "research". In the Templar section, he has a good alternate reason as to why the mi'kmaq flag could be the same as the Templar flag. I have never seen any proof that that is actually even a mi'kmaq flag. I've looked for that for years. If there is proof that they use or used that flag, I'd love to see it and I think a decent researcher would have covered that in their book. By first approaching everything assuming it's not true and if it is, cite the sources they found.
At any rate, it's a decent read if you're interested in OI but don't expect to get much new info from it. If you are a big fan of the show, it's probably worth a read as it does describe quite a bit behind the scenes over the past few years.