No Country for Old Men

I took it upon myself this holiday to read McCarthy's book and then to see the movie. I'm a huge Coen brothers fan and have read a couple of McCarthy's other books.
The movie follows the book very well. If I didn't know any better, I would have thought the book was meant for the Coen brothers to direct. Its narrative structure, the characters, and its dark sense of humor all fit their style.
As in all film adaptations, things were left out. However, the choices that the Coens made were perfect. They left out minor characters and incidents. They altered some of the sequence of events towards the end in order to speed up the narrative. For example, they brought Moss's death to El Paso where he would meet Carla Jean--not in the book. Also, they did away with the hitchhiker girl and brought in a random girl by the pool.
At any rate, these changes worked and did not alter the book's overall tone or message.
The message is an interesting question. The book is clearly about the sheriff. The title refers to him dealing with a changing world. Interestingly, because of the way McCarthy writes the book, it took me awhile to figure out that the italicized chapters (meant to be a sort of narrator's voice looking back) was Sheriff Bell's voice. The movie does a good job of getting the focus on Tommy Lee Jones as the film closes. I sensed that people in the audience were struck by the somewhat anti-climactic ending. That's exactly how the book ends. I would say it works better for the book than it did for the movie. I also felt the closure in the movie was sudden and anti-climactic. But I don't think they could have changed it without messing with the integrity of the book.
Because the movie was hyped so much, I took for granted how well the Coens cast and shot the film. The only criticism would be of Brolin as Moss. He's a little too pretty in a way to pull off the rugged, working man look that McCarthy describes. But Brolin did a great job and that was easy to overlook. Tommy Lee Jones was perfect as well as Bardem as Chigurh.
Overall, the movie lived up to the hype. The movie is an excellent adaptation of McCarthy's work. Based on an interview I saw between the Coens and McCarthy, I would say that he was pleased as well--not that his approval is required, but a nice perk.