I loved the beginning and it went well for about 2/3 of the book. I didn't care for the ending, from the time they returned to London until the end. Beth seemed to change from a forthright girl to a game-player and I didn't like that change in her character. The ending itself was totally rushed. So much more could have been done with it, especially when Neil confronts Beth over her behavior.
So the first half was excellent and the ending was just meh. Really if I could award half stars this would be a 3.5, not a 4.