I love love LOVE both Do Androids Dream of Electric Sheep and Blade Runner - too me they are the best example of a successful novel/adaptation relationship. Many plot points are the same, but Ridley Scott kinda made up the details in a way that actually fit the novel. Complementary, not identical.
Unlike Harry Potter, where they tried to keep every detail the same (except when they gave up) and hit all the high plot points and not glossing over anything if they couldn't skip it, making the films seem like two hours sitting in stop-and-go traffic.
I know The Girl With the Dragon Tattoo isn't high literature, but I thought that Noomi Rapace as Salander in the Swedish films was one of the best casting decisions I have ever seen. I swear she was born to play that role. On the same note, I thought Daniel Craig did a pretty good job as Blomkvist, although I'm afraid that's like saying Keanu Reeves did a good job playing Neo. Neither role required much expression, just a lot of hurrying around and looking concerned.