I was curious as to how the film adaptation of Gone Girl would show the story, as adaptation of an unreliable narrator and a plot where time skips about I imagine would be quite a challenge. As it turns out, they simply followed it the same way the book does, and I think it works very well.
In terms of casting, Ben Affleck is exactly as I'd imagined Nick, and while Rosamund Pike didn't initially look the way I'd pictured Amy (personally I thought of her as paler and a natural blonde), she acted the part very convincingly. The film also does a great job of showing externally what in the book is a lot of internal monologue, without turning it into people talking to themselves.
While some parts are a little streamlined, for instance the flashbacks to Amy and Nick's early relationship, or Nick's part in the investigation of Amy's disappearance, we still get enough detail and depth to get the full impact of the plot. In particular though I did feel it was a shame that Amy's relationship with her parents was mostly missed out.
The development of both Nick and Amy's characters is very well shown throughout, and even knowing the ending from the book the plot is well-paced and gripping. Not a pleasant or relaxing film, but definitely worth watching.