It's sort of a short summary of what that Air Force investigator had to say. Especially when you look up who is the recipient I don't think someone would fool around and write down crazy stories with no reliable background...

That this is no detailed report makes sense as the FBI itself afaik didn't have anything to do with Roswell and thus just can write something about what the Air Force said. I also think that a detailed report wouldn't have been appropiate as this entire document sounds like a general source of information just to inform someone with the rough details...

Maybe people will come up with other interesting documents on that matter...