For me, this book was an introduction to many a strange thing, and to a better approach to the paranormal. For this book is neither a smug debunking of the kind that Carl Sagan or Richard Dawkins are so keen on, or the sensationalised tabloid trash of the kind you get repeated continually on cable TV...
The book's attitude is summed up in the afterword by Arthur C. Clarke (who as some have cleverly deduced, didn't write this book) - some phenomena are much more plausible than others. This is a good thing, as all too often, there is a black and white approach, which seems to think that all of the so called paranormal is either real (to anyone with an "open mind") or the province of the gullible and ridiculous. So he says, quite rightly, that there's a better chance of "monsters" living in the deep ocean than in smaller lakes and lochs, which can be searched extensively.
My favourite chapter by far, is the one on Tunguska Explosion. This is something everyone should read. Here you've got a genuine mystery, and it is published with some excellent pictures from the original expedition, interviews with the surviving members etc. The bits about ball lightning and sea monsters are superb. Some of the pieces have been debunked since, unfortunately, but at the same time, plenty of things have emerged since - for example, Roswell and Area 51 were not the big legends in the early 80s that they are now.
Anyone who is looking for stuff on telepathy, poltergeists, ghosts etc will be disappointed. This is to be found in the sequel "World of Strange Powers".
It's great to read a book like this - it talks about the odd things in our world, without getting stupid or trashy. Other authors on the paranormal would do well to learn from it.