Is it fiction? or documentary? or a new kind of movie?

I wanted to like "24 City" and wish I could have liked it more, but it's a movie that doesn't attain its admittedly lofty ambitions. This Chinese movie is about the demolition of an old factory, built in Chengdu to made war materials, and replacing it with a modern factory (eponymous) - the new global economy of China replacing the old. The old was top-secret military, workers recruited from around the nation and transported to Chengdu, far from their families, paid a bonus to keep information secret, and a whole society emerged around the factory, quite separate from the surrounding city. Story told as a series of interviews with the factory workers, some very old, some young - documentary style, though I believe it is scripted and the workers are all actors (not sure of this, though), cut in with scenes of the last days of the old factory, totally dangerous and scary working conditions, and occasional shots of the construction underway for the new 24 City. Some of the footage in the old factory is great, and the interviews all include a scene in which the director poses the subject (or subjects, some are couples, groups of workers, friends) for a very long shot - all of these quite extraordinary. We do learn, through the film, about an aspect of Chinese history and contemporary culture, but unfortunately the stories of the workers, the interviews, are not intrinsically all that interesting, and when they are they're just spoken narratives rather than dramatized events (as in filmmaker's recent movie about a Chinese city soon to be flooded - much better movie, don't recall its name). The documentary-fiction style is often used for highly polemical purposes (Michael Moore) or for satire and comedy (Best in Show et al.), but here the director uses it as a way to tell a story within a historical context, but it just isn't as compelling as I'd hoped, and it times it was difficult to follow the narrative - to know if the workers were already in the new factory, for example. I'd see more work by the director, Jiang-ke I think?, and really like his The World, but this was not a movie for everyone.