I happen to like really dense non-fiction, especially looks into complex webs of corporate malfeasance/mismanagement, thus House of Gucci was a super solid read for me. But I think most people who saw the movie/came for the true crime drama will be annoyed/frustrated/disappointed. And even with my inclination, the book frustrated in a few points, so it's not a 5 star/must recommend from me, either.
But, man, is it an eye-opening picture of the rise and fall and rise again of Gucci! And that's really what it is: this book is 90% solely about the family and the business, not about Patrizia Reggiani and the true crime aspect of it. I really liked how it started at the beginning and then moved chronologically through the history of the company, via that lens: the company. The book goes long stretches focusing solely on the nitty-gritty of business decisions and disagreements/literal fist fights/backstabbing/lawsuits with nary a mention of Patricia/Maurizio's marriage/personal lives even though you know, logically, many things were happening concurrently.
It would be interesting to see a differently lensed take that blended the two narratives together in one stream for context, as I did find myself wondering more than once "ok Maurizio's is acting like a giant asshole/moron during this period at Gucci--how does this dovetail with what was going on with his marriage/at home?" Especially given Patricia's eventual diagnosis as having npd and, well, that she murdered him... one can only one how much of his business spiral was connected to his personal spiral.
But for me, the business-only focus was certainly interesting enough. I came away with a pretty solid understanding of the family, the culture (both in the business, the family, and Italian business culture), the various toxic dynamics and the broader business/industry picture throughout the years. If you love fashion, fashion history, and US & international corporate/business/stock/conglomerate/investment nerdery... it's really interesting! However it's also LONG, and a dense read. I think those who want the juicy narrative/true crime parts will be too bored to finish it, honestly.
The storytelling style sits between "a bit dry" and "slightly narrative"--there are some vividly painted scenes, to great effect, but many stretches that FEEL like informational journalism. It's fine, but on the scale of "evocative narrative journalism that reads like fiction" and... not that--this sits closer to "straightforward, super in depth piece of long form journalism." So it's not one I'd recommend to a "reluctant non-fiction" reader, basically.
Where I gave pause more than once was the sourcing where specific scenes of Maurizio and Patrizia's relationship was concerned. Unlike some non-fiction that makes clear what the sources are for select stories, this book doesn't do that--at least NOT in the parts about the "juicy" true crime/personal stuff. Without such sourcing/citations, I just stopped more than once at a incendiary description of Maurizio getting violent with Patrizia, for example, or saying something REALLY nasty... and wondered "source?" Because if Patrizia is that source, as I suspect for these instances that were strictly between them, it makes me... itch in a very uncomfortable way to describes these scenes as fact. The man is dead--he cannot defend himself. Did he really choke Patrizia and say this will make you taller?! Ma'am, I'm going to need an independent, corroborating source on that. I'm just not 100% comfortable with accepting Patrizia's telling of... anything as objective fact. And if there was additional sourcing, as I said, it's not said on the page. It made me super uncomfortable.
So I can recommend this with caveats, per above. A great read for a certain kind of reader/non-fiction fan. Did make me slightly sad we didn't get House of Gucci as a Succession-esque mini-series b/c it is RIPE for that... now I know why the movie couldn't decide who the main character was, or what the main story was... b/c it was cherry picking the small amount of true crime from what is really a family and business saga. And that side of it is SO much more interesting than depicted in the film! (also wow was Adam Driver horribly miscast. Jared Leto too, imo)