I love "Planet Earth"! Even if you're not super-into nature shows, this groundbreaking documentary series about our environment is one beautifully filmed how-did-they-get-that-shot moment after another... and Oprah's "Life" just pales by comparison to Sir David Attenborough's buttered-crumpet voice. Download the first episode for free at iTunes and see if you don't agree. (You have to have iTunes installed, but it's free.)
I actually own the series, which is available for a pretty good price over at Amazon, and if you really agree with me on the Oprah thing, you can pre-order the David Attenborough version of "Life," without her cornball script that tries to turn animals into courageous single moms. Bleh.