This winds up being a great adventure story. We get to find out what happened to Pete & Ariel after the end of their story, and the world of the Change starts to make a lot more sense than it did originally, but I really think that it is the little things about this story that make it amazing. The sea serpents mating in the ocean, Yan having a poster of the first moonlanding on his bedroom wall, the surfliner railway car that Fred & Yan turn into a home, potions brewed up over a camp stove and stored in a thermos, 'Ariel' the book showing up in this story - written by Pete, published by someone who stumbled across the manuscript and turned into an instant hit. One of my absolute favorite things is the centaur funeral custom: telling stories about people that other people have lost.
I only read this because John Scalzi wrote about it so glowingly (and the description of the book written by Steven Boyett sounded interesting too). I picked up a copy of Ariel based on that recommendation, and was a little disappointed, but reading Elegy Beach made it up to me. It isn't perfect, there are enough little details not quite right about the world to jolt me out of full immersion, but there are more than enough totally awesome bits to make it totally worth reading.