I have only watched the first four cds, but struggling to make my mind to watch the rest! Does that mean the content of the documentary is not good? May not be, but the unfortunate fact is video quality is very low. Blurred, disturbed, breaking video always. We are living in blu-ray era, so be prepared to get compared against the likes of bbc planet earth. Also there are too much of interviews with individuals - its always good to know the opinion of some experts, but too much is not acceptable. In every episode, interviews would cover a good 40% of the duration, if not more.
All in all, if you are a documentary lover, these topics would encourage you to buy, but this is not the type what you could enjoy.
(If you watch this in 14 or 18 inch small screen, may be ok. But if you've got a HD television over 40 inches, think twice)