I have read three total. The first one in the month following the film's release, the other two somewhat later. I don't find AU fanfics very appealing, and have only read and finished two. One, I finished out of a sense of time invested, and one I completed because I liked it.
Ennis - Probably not the greatest, but definately filled a cavity left in my heart, left by the film experience.
Somebody New - Time Invested, didn't really care for it, but after 1 million pages of lousy dialect I thought I should finish it.
A Love Born From Steel - I liked it. Genuine charectarization, honest writing, again despite the AU aspect of it, but if I had never heard of BBM in any form I would have enjoyed this.
Strangely enough. The only "full length" story I wrote was, in the end, an AU. Go figure...we all sell out for an audience...LOL...eventually.