I agree that Brokeback Mountain is quite overrated. Some of the acting was a bit over the top as well. I saw it at one of the very first screenings and Jake Gyllenhaal was there to talk about it afterward. I found it very interesting to hear him pretty much come out during that talk.

In paraphrasing him, he said:

At first I was very intimidated working with Heath (Ledger) since he grew up on a ranch and was so comfortable with riding the horses, etc. Then when it came to shooting the sex scenes, I felt better, because here was my opportunity to bring Heath into something that I knew about.