Book-to-Movie Law states that once you have read the book, you are bound by the media to go see the movie based on said book, and therefor compare to two.
The book was a DNF for me. Could not get into it no what I tried. The movie was a DNF as well. How could a premise with such promise fail in both mediums?!? I think my issue with the book was that it jumped right in to the story with no starting point, no place to introduce the characters or get comfortable with them. It was unreadable and felt much too unfocused for me to get very far at all.
When the movie came out and the trailer was shown I thought Ah-Ha! Film would be a much better way to show the friendship of two individuals progress over a long period of time. But no. Anne Hathaway is tortuous to watch fumble about in terrible costumes meant to represent the various years. And the guy who played Dex was neither attractive nor delightful to watch either. So I guess it turned out that one day of talking/meeting up with each other really didn't translate well to film. I think there were just too many disconnects for me to enjoy this story.
Bottom Line: The movie was easier to watch than the book was to read, but I would pass on both and find something much more interesting to watch/read.