Not knowing much about this story I was naturally intrigued to watch this doc. In a way, its a shame that even a few of the major elements of plot are given away in the promotion for the film, because its clear the film makers approach is to not take the viewer's preconceptions of the story as given, and the initial pace setting up the context and characters reflects this. It is an amazing story, and for the most part well told in an atmospheric noir fashion.
Personally, I am in favor of some kind of initial build up, as most modern docs, and fiction films too, have a pretty rushed pace. I liked the tone and eerie atmosphere in the first half, especially when we hear from some pretty amazing secret tape recordings. But I also feel that in the second half something was missing, I wanted to hear more about the couple's experiences in North Korea and I get the sense that much was left on the cutting room floor. Perhaps there will be a directors cut?
Overall, it is a pretty compelling documentary worth your time, as so much of it simply beggars belief, but I do wonder if a more interesting approach to the story could have been found. Having seen the excellent Listen to Me Marlon, could the film makers could have achieved the same kind of effect, just using tapes and movies?
One thing though, if you are going to watch it, don't read anything more about the story, just do it.