I'm less than 200 pages in, but it's a totally engrossing world that John 'don't call me' Shirley has created. He has created a completely new story within the Bioshock world as a prequel, and is filled with great attention to detail, convincing characters, insight into Raptures history and how it was created, more insight into Frank Fontaine who would go on to be a major player in the original game, and so much more. An involving book, and PROOF that not all videogame books are terribly written. I need to read the whole book for a complete opinion, but honestly this book deserves to be read, even if you haven't played Bioshock before, because the Sci-Fi premise is fascinating.
OK so I finished the book recently, and I'll say that it manages to keep the superb atmosphere throughout the whole novel. Towards the end things are probably sped up a bit too much with a lot of story crammed into the last 50 pages, but other than that, I can't fault this book. On the 2nd readthrough you know the characters and can form a better picture of the early chapters in your mind, and that's what I'm doing now.