The bad far outweighs the good of this book. The editing is weak (I found a number of misspellings - at least in the Kindle edition). Most citations and resources cited are from the 1950s and 60s and all of the more recent evidence and testimony is not discussed severely limiting the scope of the work. Too often than not the author forces his conclusions. Too often than not he is unaware of the more current literature and discussions which seriously undermine this work.
The best part was the outdated discussion over the various propulsion systems of the UFOs. Not recommended.