I have now finished watching this entire box set - my first experience of High Definition and I was blown away by the picture and sound on the first 4 discs.
I have awarded 4 stars for 2 reasons...
1. The 5th disc is not in high definition.
2. Unlike the DVD box set, this box set does not contain any 'making of' footage at the end of each episode.
As for the main content of the discs I cannot fault it, excellent narration by Attenborough and ground-breaking camera work.