I've watched almost all of the episodes of the BBC version and have seen a few of the US version. They seem to be cut/edited a bit differently, and as wish mentioned, the narrators are different. It very well may just be me, but the BBC/Attenborough one seemed to be done in more of a "classic" documentary style with regards to the wording of the narration. The US/Weaver version felt to me like the narration was aimed at middle school kids. (Paraphrased example - BBC: "After a long winter of confinement, the polar bear slides down the snow-covered hill--possibly to clean her fur; possibly for the joy of it." US: "After being cramped up for the winter, the polar bear takes a chance to play and sleds down the hill.")
I did not think it was sold in the US version, but I saw the US on Discovery HD while I received the HD-DVD as a gift. Attenborough is many times better in my opinion. Weaver's voice ruined it for me the first time. I found it to be much more enjoyable on HD DVD. Oh, and I think the BD uses identical encodes, so get whichever one is cheapest.
I think the video quality is the same. Both are wonderous. Only seen short clips of the American version, but it was better than the HD cable. The BBC version is amazing but it seems to be the same PQ of the US version.
The Briitish narration just seems better to me, although I liked it when I watched the Dicovery HD with Ripley, I like the Sir David narration better. YMMV.
Planet Earth is a beautiful bookend to, "The Living Planet" series which was in itself another great nature series and was written and narrated by David Attenborough (http://en.wikipedia.org/wiki/The_Living_Planet) . Removing Attenborough's narration from Planet Earth was more than just stupid.
I actually prefer the US Edition, mainly due to the musical cues used. Especially the opening theme music, which everyone loved and it sold several hundred thousand copies on iTunes, where it was released exclusively. The music is much better IMHO.
So is there a plug about global warming and the evils of man at the end of each segment on the UK version?
Don't think so as far as the end of "each segment," but they definitely get a little preachy at the end of the final episode. That said, it's not really abrasive and only the REALLY picky will get miffed about it.
David Attenborough, has he been around for ever, I swear I remember his voice in old school films in the 70's, yes I'm old and prefer the geezer narration, it just feels right, and I do like Sigourney Weaver, just not narrating.