Visual evidence of evolution. The drama in each ep. surrounds eating (hunting or surprising prey, evading or escaping predator, and fighting it out, else scavenging or waiting for weather to change), mating (demonstrating superiority via dominance, endurance, beauty, etc. and then sustaining coupling), and maintaining one's family. Not so different from humans. Both perform in myriad interesting permutations. No sea.
It doesn't get much better than this. The epic music (the theme is an instant classic), the clever and emotionally-resonant stories, the amazing camerawork, the unique wildlife moments captured, Attenborough's timeless narration ... my list of favorite things about the series goes on and on. I will single out the production diary at the end as a feature I loved and hope to become a documentary staple.