The book is indeed very long, sometimes it feels that it could some parts could have been skipped or summarized. Regarding the content, it basically tells the story of Ellison until the late 90's, diving into his personality. At the same time tells the story of Oracle. In some chapters the author focuses on the company and in others on Ellison. I personally found the first half of the book very interesting, basically because it tells how Oracle was started and came to be the number one database company, when at the beginning was probably the least likely to become the market leader.
I learned how much you can achieve with thinking differently (and a good marketing strategy). I think the basis of Oracle's strategy is the fact that usually people follow fashion instead of reason, as Ellison has mentioned. So instead of preaching customers to follow reason, Ellison decided to go for fashion. It didn't matter that there were far superior products to Oracle, what mattered is that people bought Oracle and that big customers did, so that small customers also did by inductive reasoning. Of course, this only works at the short term, but why would you care about the long term now?, the long term can be addressed later. As Oracle did later with Oracle 8 (or 7, not sure) which was the first Oracle DB that did work as promised, due to hiring ivy league students. The technical strategy to achieve long term market leadership is not mentioned that much and I think is equally as important as the marketing strategy.
Andrew Mendelsohn writes about this strategy and makes the argument that Oracle became a leader because they kept adding features to the DB that other companies offered as other new products, while they also focused on maintaining a technical differentiator against the competition (thinking differently is key). I would recommend this document to better understand the technical side of the strategy: The Oracle Story: 1984–2001. IEEE Annals of the History of Computing.