This screening that people are talking about was actually a TEST screening, not an advance screening... aka, it's a TEST to see what people like and don't like, and then they fix things... as for the music, what we heard during the test was actually temporary music. I heard a rumor that Mark Isham (Crash, River Run Trough It, etc) is doing the music for Not forgotten, so that should be pretty great....
I would DEFINITELY recommend this movie. Personally, I thought it had some really great twists and turns, and had a really cool dark feel to it, and a fascinating view of the dark underbelly of Mexico's low lives...Seriously, I did not see the ending coming at ALL. If I had to compare it to something, I would say it's like "Traffic" meets "A History of Violence". Oh, and obviously, Paz Vega's really hot.