It rather reminded me of "Last Picture Show" in its treatment of conventional-yet-loveless relationships. Also the sets and pacing were similar. Fairly slow, but rewarding.
The sex stuff wasn't as bad as I'd heard. If you've ever sat through five minutes of "Queer As Folk", you've seen worse.
Edit: Just found out that "Brokeback Mountain" and "Last Picture Show" were both written by Larry McMurtry.
Dang I'm insightful.