I'm 40% of the way through. Overall it's a really good book on the subject. Dolan is a professional historian, so it has those virtues, such as being critical of the sources and, what I liked especially, he gives the historical context of the different periods of UFO sightings. He is especially good on the late WW2, immediate postwar period and the early Cold War and how that interacted with the pheonomenon. Unlike his two monographs on UFO's and the National Security State this one is much more accessible to the general reader, so it makes a great introduction to the topic. He sticks closest to the nuts and bolts hypothesis, though, and as yet, I've seen no mention of Keel or High Strangeness. But unlike his previous work, he does spend time at the beginning looking at UFO-like phenomena throughout history going back to ancient times.