Just finished reading the prologue book. The writer is the same guy who writes the story of the game. His resume also includes the story of KoToR and another NY Times bestseller StarWars book. The story in the book itself is above average. It begins with nice, fast paced action, then slows down, and then ends with something that you do not expect from the main character. However, it will give you lots of information about the mainbad guy, Saren, in the game, and also, the admiral (Anderson) whom Shepherd was speaking in the beginning of trailer. I also bet that we will see more characters from the book in the game - though a little bit aged..
Although the story is above average, the backdrop world - or should I say galaxy - is excellent. You will understand why they call it "jack Bauer in space". Spectre, of which Shepherd is also a member, is an elite group, whose members are few but kind of above the law. In order to protect the galactic peace, they are allowed to do anything: this includes torture to extract information, setup a team as a bait (it does not matter if they survive or not), even commiting actions that result in loss of thousands of civilians life - if all of these leads to saving of billions of life, that's what a spectre -you- should do. That's why the creators of the game says you will face though choices throughout the game, and reading the type of tasks given to spectres in the book, this is something sure we will see in the game.
After reading the book, I also know think that Bioware creates an excellent setting for themselves. Being a shepherd means you have to take any task that is given from the council, and it does not necessarily mean that it is related to main quest. I think with this in hand, they can easily expand game by adding quests as DLC. Even maybe, we will see some episodic content, who knows...
Anyway, the book is worth reading, at least for getting more familiar with the setting and the characters. I am alot more excited for the game now!
Thanks a lot. I was planning to ask about the book but not seeing many reviews online and lack of mention here, I thought there wasn't much interest. Now I have to pick a copy.