Speaking of the Hobbit, I'm having a hard time even calling the films an adaptation.
it's a different beast altogether. I read the Hobbit when I was a soldier, and from what I remember with all the stress around, the Hobbit made me think about green hills, and the peacefulness of the wilderness and going out to meet it. The Hobbit is very light reading. The first film, although great, is a huge production that completely goes against my peaceful vision of the book.
Tolkien's literature usually makes me feel about the outdoors, green environment, a more innocent world, and even good pipe smoking and good food. The films are dramatic, swiping, and take you into the thrill and drama.
But yeah, it is definitely great production, well invested and inspiring.
There are some cases where films meet or exceed an awesomeness of the book. I agree with Paul, while I liked 'Do Androids Dream of Electric Sheep?' I can't really say that it is a as memorable as Blade Runner. And while the book 'The Princess Bride' is really great and funny, the film is just epic, even some of the changes in the plot make more sense in the film adaptation.