A very extraordinary box set in every way. I bought this as I was intrigued by the subject matter but must admit I was quite skeptical, and this boxset does a great job of laying out very well thought out, intelligent arguments in a very professional, well presented manner. It's easy with this material to be too bombastic or fantastical and - whilst the series does present some truly astounding theories - each one is well evidenced and presented as a question, rather than as fact. This is very much the Von Daniken way and is a nice dovetail to his works. Some of the 'experts' are a little too myopic in their views, however it doesn't detract as the strength here is in the evidence presented - it doesn't try to sway you with faux-scientific opinion, it just serves up a series of facts and asks you the question "what do you think?". And that's it's great strength.
Would heartily recommend, not just for UFO/Alien enthusiasts, but for anyone with even the slightest interest in history, astronomy, evolution or civilisation.
Very good material, very well presented, excellent stuff History channel.
(Small point of note, I have seen this on the History channel where it has an English accented narrator, this box set has an American narrator - as I presume this is the original recording - however, personally I think the American narrator does a better job).