It was a great series and was beautiful to watch. Some of the footage of the animals was the first of it's kind, such as a Snow Leopard making a kill, a lot of the undersea scenes, and footage inside caves. I've heard some people say they would have preferred having Richard Attenborough narrate rather than Sigourney Weaver, but it wasn't distracting to me (the DVD set has Attenborough). I think it's a good buy if A. you love nature shows or B. you want something that you can watch with kids that won't make you tear your hair out.
I enjoyed it a little more than Iron Man 2. Once I started reading vague references to there being a "twist" about the Mandarin, and that he was in cahoots with Aldrich, I pretty much called exactly what it was going to be.