I loved it. I'd give it 90%. If you loved Se7en or Fight Club you will love this movie for sure.
Rosamund Pike KILLED it. Ben Affleck was good. Not stellar, but good. The woman who plays the sister is hilarious, Tyler Perry is great. All around solid cast.
I thought the 2h30 runtime would make it seem long but NOPE, David Fincher knows how to keep you interested.
I personally loved the third act and thought it was a complex, typical Fincher ending, imho a lot of journalists or people saying the ending was awful are just too stupid to comprehend the intended message.
I saw John Wick last Friday but preferred Gone Girl in terms of entertainment value.