So I managed to finally get a copy of this book last week after waiting 10 days for my special order (none of the bookstores in my area had it in stock), and I have to say, it was definitely a great read.
For those who are looking forward to the release of Mass Effect for the Xbox 360, I dare say, this is a must-read title. Not only does it serve as a prequel, chronicling the events leading up to the storyline players will face in the game, but it also fleshes out quite a bit of the ME universe helping you to understand a bit more of how Humanity actually managed to become a part of the community of space-faring races, and a bit on the other races themselves, as well as inter-race politics and issues. It does read a bit heavy on the informational side early in the book, but if you're the slightest bit interested in the universe, this won't bother you at all as you'll be scrounging for every scrap of info you can get. As it goes on, it becomes a lot more focused on the story at hand, which although it ties up nicely, does tantalizingly leave you wanting more.
Something of note that I really enjoyed, was the way they dealt with the common questions of a fictional sci-fi setting, such as, "why are most aliens bi-peds like humans?" and "how come everyone can breathe the same air?". The theories presented in the book serve well to give somewhat realisitic (in terms of the universe) answers, although no decisive conclusion is met.
Overall, I'd definitely say it's worth the price of admission (US$7.99) for an early glance into the behemoth of a world that is Mass Effect for anyone with even a passing interest. So pick it up, and get yourself up to speed so when November hits, you'll be more than ready for the adventure ahead. :)