Before you read any further I would like to let you know that this blog will have spoils.
So basically want I want to talk about the book is mainly its links to Halo 4. Jul 'Mdama, a Sangheili serving against the Arbiter and hated humans was abducted by humans and taken captive to the Forerunner planet, Onyx-Trevelyan. He was allowed to explore Onyx with permission from the humans and was escorted by an old Forerunner Huragok that the humans found. He spoke with the Huragok and the Huragok mentioned Requiem and the Ur-Didact. Eventually Jul found a Forerunner building that contained portals to other planets. He found and entered one working portal not knowing where it would lead him. In the end it led him to a planet called Hesduros that also contained Sangheili. We always thought that Sangheili only had one planet but they actually have "two!" These Sangheili did fight a little for the Covenant but hadn't heard from them in a year. So these Sangheili don't even know that the Human-Covenant war was over. But these Sangheili seemed to hate humans with Jul as well. At the end of the book, Jul looks at a Forerunner building on Hesduros and discovers the coordinates to Requiem, sleeping place of the Didact. So this may be why there are Sangheili fighting humans in Halo 4, because there is another clan of Sangheili. Halo 4 though is 4 years later after the end of the book. And Jul leads this new army of Sangheili, Jackals, Grunts, Hunters etc. As seen in the Halo 4 Terminal Trailer. Jul finds Requiem four years before the humans and tries to find the Didact, because the Huragok told him that the Didact hated humans and Jul wants the Forerunners on his side. Note: Jul isn't a religious Sangheili like many of the others who serve against the Arbiter.
Also, the UNSC Infinity is in this book. You may be wondering how it has Forerunner technology plus UNSC tech. Well remember that Forerunner Huragok I mentioned, well there were three of those found and the humans also got a Covenant Huragok too. These Huragok mated ant had more Huragok, then the humans made them work on Infinity and added Forerunner tech. They also added this to the UNSC frigate, Port Stanley, and a Pelican called Tart-cart. So this is how the UNSC Infinity got a hold of Forerunner technology.
So Halo 4 in a way is a sequel to the book, half of the book anyway. I can't wait til Tuesday. So just for those of you who don't like reading but play the games, here is some answers to your questions.