I just finished reading Cecilia Aherns "PS, I love you", and I absolutely loved it! It's quite different from the film, in a good way, as it usually is with these things. The ending really surprised me, I was kind of disappointed at first, but it was a good ending really.
I would recommend this book to any girl/woman, just be prepared to cry quite a few times when you read it, both because it's sad and also of laughter.
I have to say thought; it annoys me that the film is set in America when it's not supposed to, just like "Confessions of a Shopaholic". Can't American film-makers understand that things does actually happen in other countries as well?