Talking from my experiences in the Mass Effect universe, everything in this book fascinates me, since I have spent at least 200 hours living in all 3 games. Being able to see the thought process behind each of the races and the culture behind them, makes you realise the love that was put into the games. The book doesn't just cover the races it has concepts for the various location visited in the story from the Citadel right back to Earth in Mass Effect 3. They even make it very easy to find a particular location or person you wish to look up as the book is divided into the 3 individual games.
This being a concept art book it is very hard to describe how good the quality is. This is 186 pages of fan service giving us an insight into how Bioware were looking at the world they were building, and where things could have went with just a few different choices. This is a very specialist book, directed more to people that have played and loved the games. For a fan of the universe I would highly recommend it. And even for the aspiring artists wanting to get into Art design for gaming, a little more knowledge of how it is done in the big leagues won't hurt.