My wife and I saw it recently. We both appreciated Ang Lee's ability to create ambience. I walked away with the same "taken far away" impression I got from "Crouching Tiger Hidden Dragon." She focused more on the social mindset of the time and how it affected the characters.
The cinematic shots of the Wyoming landscape and wide angle shots really highlighted several points behind the movie: 1) despite the vast expanse and possibilities that American culture affords there are still certain areas where one can feel claustrophobic and severely constrained (in this movie's case, it was about WHO the leads chose to love) 2) Brokeback mountain was not only the place where the two leads first expressed their desire for each other it was also their refuge... their sanctuary. The story was set in the early 60's and in rural Wyoming which was several cultural spacewarps away from San Francisco or New York's Greenwich Village where the Gay Rights movement centered. Indeed, it's remoteness and isolation gave the film a great formula for framing the feeling of frustration, hopelessness, and desperate longing within such an otherwise expansive and limitless landscape.
One particularly interesting scene was where Ennis (Ledger) beat up on two biker assholes who were disrespecting his family. In that one scene, backdropped by exploding Fourth of July fireworks, Ang Lee strongly makes the point that homosexuality has nothing to do with manliness. One can both be gay and still be "manly" (in the traditional sense). And this is the point that makes the film's elements even more troubling to the lead characters. They embody the American ideals of machismo and manliness--Ennis' silent, strong, and protective cowboy image sums this up. Yet they are not free to be who they are or truly choose (in society's eyes) who to love. That is the perfect lead up to the tragedy in the movie.
This is a very tragic story of unfulfilled love, of regret, of being "not man enough" to accept one's self and make the right decisions. Given the homophobia (with often fatal consequences) that informed the era the lead characters lived in, one can't really blame them for making the choices they did.
Here's my rating:
Acting -- Top Notch (except maybe for Ann Hathaway--although she did appear topless

)
Story -- Very troubling, moving, and, ultimately, haunting.
Direction -- Ang Lee did it again. He used "Crouching Tiger" to show that Chinese martial arts flick can be moving, dynamic, and liberating. In "Brokeback" he used the expansive Wyoming landscape both as a foil to the inner tensions of the main characters and as a refuge for socially taboo affection.
Good movie. Definitely requires an open mind to see.