The plot is a fairly beaten to death one. This book reminds me of the movies 'Buried Alive 2', 'Double Jeopardy' and some parts of 'Unfaithful'.
Some parts of the book were poorly written while parts where the Flynn describes marriage and its compromises rings true.
The ending of the book is interesting but I felt it was an open ending. I wonder if Flynn plans a sequel. Which I would surely read.
In short, it is the perfect book for a long-ish flight or commute. Its interesting enough to keep you mindlessly engaged - heavy on drama and light on detail and depth.
Gone Girl is the first book I read on a Kindle and I love it... the Kindle not the book. :)
Read more about Gone Girl on Goodreads here.