I hate previews because they give away too much. I'm glad I didn't see the preview for Salt - no spoilers. My wife and I thoroughly enjoyed it, on the edge of our seats throughout. With all the action, and all the bad guys getting killed, there was surprisingly little gore, and I'm not sure how may people noticed this, but when hammering the good guys, she mostly incapacitated them without killing them. Nice touch. I could easily have watched for another couple of hours, but now I have Salt 2 to look forward to.
My wife and I took our three grandchildren (ages 4, 6, and 6). It is unusual for them to sit still for any length of time, but they were rapt throughout. A very entertaining and often touching movie.