I'm going to be very careful in my comments about Fire and Fury because this is not in the politics section. If the mods need to move this, so be it.
I'll start by saying that it was an interesting read, but in more of a fun popcorn way rather than as a serious tome. Clearly it was produced in a hurry, as there are numerous small errors (spelling, grammar, etc.) and some internal contradictions. It has to be read with a large grain of salt.
I didn't get a lot of new insight into the current POTUS - I think he's already pretty much an open book what with off-the-cuff remarks, speeches, and of course tweets. The book fleshed out his portrait a bit, but all in all there wasn't anything that really startled me about Trump himself. (Although the eating-cheeseburgers-in-bed thing was a yucky revelation.)
However, I did glean insights about many of the people Trump has chosen to surround himself with. One of the early themes in the book is that no one on the campaign expected Trump to win, so they did little of the normal preparation that presidential campaigns usually do once the nomination is in hand. Once he won, they scrambled. The existing campaign staff had little to no experience in actually governing, and the infighting for influence and titles was vicious. They had trouble hiring experienced competent staff due to strict "purity" tests (you flunked if you'd supported other candidates or ever stated concerns about Trump) combined with many regular insiders' reluctance to work for Trump. Also, Trump and many of his staff figured that they'd won despite the "experts" so that made them smarter than everyone else and they had no need to bring in knowledgeable people. One example of how this amateur hour played out - no one Trump trusted knew how to draft an executive order, so you have the spectacle of Stephen Miller trying to figure out it out via internet searches. The order that Miller eventually produced was the first "Muslim ban" which was immediately and universally rejected by the courts. A properly drafted EO may well have avoided that fate. There were a lot of unforced errors like that simply because they were all learning on the job, but wouldn't admit that perhaps they needed to consult with people with more experience and expertise.
I think the very fact that Wolff was permitted to wander around the West Wing for months unchallenged speaks to the lack of normal organizational process - can you imagine that happening in any previous White House? Bringing in Kelly seems to have brought some regular order to the West Wing, but of course the uncontrolled wild card remains POTUS himself.
All in all, I thought it was a fun gossipy read about the characters that populated the inner White House in the early months. Learning more about those characters is especially interesting now that many of these same characters are being questioned by Congressional committees, and of course Mueller.