I read this book in grade school and decided to pick it up again from Amazon. It's a fun read, but doesn't develop any of the characters much beyond 2 dimensions (unless you count their alternate universe doppelgangers).
The story itself is about an Upstate New York town in the decades following a nuclear war - a war that broke out in the 60's. The townspeople begin having dreams in which they appear to be living in a future world (one with computers, fast food and everything else we're familiar with here in reality) that is on the brink of their own nuclear war. Slowly, one reality begins to merge into the other...
Fun concept, but it doesn't really get moving until you're in the last 20 pages of the book. The rest of the book tries to draw out the characters, of which there are too many to do any one character well. The result is a lot of useless information - not to mention several HUGE dead-ends. The author builds up about 3 very interesting story lines, follows them for a few chapters, and then never mentions them again.
I might recommend this book to an adolescent boy growing up in the Cold War. But I don't think there's much to be gained from this book unless you're just trying to compare apocalyptic books. In that case, the alternate-reality storyline is mildly fascinating.