At more length:
First, the negative points. According to the (small amount) of advanced publicity I heard, this book was to “fill you in on what happened to the various characters since the original run of Twin Peaks ended”. There is a little of such material, but very little indeed. Instead, it is much more what it says on the tin: the history of the town and characters BEFORE the original run (which I quite liked, so more on that below).
One of the main narrative drivers of the book is the question of the identities of its twin narrators, The Archivist and The Analyst. This has, for me at least, a negative payoff. The identities are revealed near the end of the book in such a careless fashion that it left me actively wondering why the hell those identities were ever obscured in the first place. (I mean by the characters within the story; I understand its value to the author as a narrative device.)
The copyediting is atrocious. There are missing and misnumbered footnotes. There are numerous copy and paste errors. Copypasta errors are annoying in any context, but when they occur inside documents that purport to originate before the invention of word processors, that torpedoes my suspension of disbelief.
So much for the problems. On the good side, I did HAVE excellently-suspended disbelief apart from that. Surprisingly, and pleasingly, a significant majority of the book is well-researched historical fact (with Twin Peaks connections layered in). Some of it I was already aware of; at other times I would head over to Wikipedia for verification (and more details). As any lover of the subject knows, history contains quite enough surreal, fantastical, and mysterious events to fit right in with the world of Twin Peaks.
Unsurprisingly, given that he was one of the show’s co-creators, Mark Frost perfectly captures the voices of the familiar characters, and does a good job giving the unfamiliar characters distinctive voices and personalities.
One of the central characters, “familiar” only from a couple episodes during the low point of the second season, turns out to have unexpected depths. Doug Milford did a lot more during his life than just feud with his brother and run the local newspaper. He was involved in government conspiracies since before Roswell. And yes, the hints in late season two are being doubled down on: the history and cosmology of Twin Peaks is intimately interwoven with that of UFOs. Not in any way as simple as a straightforward alien invasion, of course…
As I said, this is indispensable for hard-core Twin Peaks fans. I would also mildly recommend it to fans of guerrilla ontology and/or paranoid paratexts.