Unquestionably, this is a love story. However, "love" might not be the real theme that Krauss delivers. Behind the story, it is about true and false, real and illusion, the absolute loneliness and the denying of the existence. Overall, this is a quite successful work. However, I feel that the story is over-plotted, and writing elements are over-used.
The book I read was the first edition published by W. W. Norton & Company in 2005. ISBN 0393060349. Hardcover.