I hadn't read the book and knew nothing about the plot outside of the basic "Wife goes missing and husband is accused of murder" angle. I think David Fincher is a bit of a genius filmmaker, so I went to see this on his merit alone and was not disappointed. The acting was superb, the plot shifts caught me off guard and the atmosphere of the film was pitch perfect. After watching the film, I read that spoilered synopsis on the first page and it really just doesn't do any justice to what you'll actually experience -watching- the film.
9/10 for me.