It is odd that a mix of Meet Joe Black and Forest Gump wouldn't come out as a fantastic movie, but when you mix it with a metaphoric bottle of sleeping pills as Fincher has done, you accomplish the impossible.
The movie was not bad, but nothing exceptional either. It was overlong and boring. There is a difference between this and a good 'quiet' or introspective film. This film was not a great quiet film. The writing was mediocre so the sparse words, long stares were emotionless and empty. And the music doesn't help the story. It makes it less dramatic and less interesting.
Yes, Desplat does interesting and analogous things in his music with the story, but that must come secondarily to the overall listening experience. Unfortunately, it does not.
A prime example is the love story. The movie portrays it very meagerly; this is in large part due to the characters and the writing, but also due to the over 'cerebral' writing style that lacks anything passionate to draw you in and make you remember or feel anything for these rather boring characters.
This is not an exceptional movie and it is not an exceptional soundtrack. I'd have given the score a 2.5.