David Brin is at the top of his game.
I fully expected him to wrap a great story and lots of cool characters around a big idea in Existence, but Brin didn't settle for just one big idea. Or two. Or ten.
I think he used all of them.
In every chapter, in every point-of-view, in almost every scene of Existence Brin treats the reader to fascinating and profound concepts. I'm not world-weary nor well-read enough to know how many of them are original to this book, but as a storyteller I'm frankly amazed at how deftly they're all woven into one novel. The result? Existence is a long, delicious read, rewarding at every step of the way, while still being infuriatingly tantalizing.
Existence is a first contact story set in a rather perilous near future, but it's too realistic and too optimistic to be one of those trendy dystopias you kids are all about these days. You'll recognize yourself in one or more of the characters, you'll see the consequences of your actions 40 years from now, and you'll get a believable resolution to the Fermi Paradox; one which doesn't invoke gods, time travel, or Imperial Galactic quarantines.
I'm not just recommending Existence to you because Brin wrote an introduction for me. This is a book which managed to far exceed my already high expectations. It's smart, it's fun, and I'm afraid it's also terribly important.