First of all, it's hard to argue with free. This PDF could consist of a front cover, a back cover, and five lines of text, and would still be considered by many to be "good value for money." Now that that's been said, we'll move on to the review proper.
If I could sum up with book in as few words as possible, it would be "26 pages of flavour text." If you're looking for some subtle inspiration for where to take your team next, what they might do, and who they might see there, then that's great. If you are looking for maps, character sheets, environments or even useful illustrations, then this is not the book for you.
On the credit side, that does make it easier to use, in a way. It leaves you to work out your own stats, which may make it easier to introduce the ideas and locations into your game. Your game might not even be Trinity, any semi-futuristic settting would work.
It has some "news articles," a few "reports," and a few "emails" all helping to give an open-minded reader a taste of life in one of the "Ocearcologies." The main body of text itself is also written in an appropriate style; for example, Pearl City's entry is written like a tourist brochure, advertisements for ticket sales included.
For the most part, the text is well-written and entertaining, barring a few spelling mistakes and the odd error in grammar or punctuation. Illustrations are few and far between, the most useful being a map of the world.
So, why a middle of the road review? Because while there's nothing really wrong with it, there's not really anything right with it, either. There are no "that's fantastic!" moments. There are no breathtaking images of sweeping oceanic vistas. And, as I said earlier, there are no rules, no technical data, nothing "hard." It's all fluff. It's good fluff, but fluff nonetheless.
But who cares? It's free, right? Go for it, you might like it.