I agree with everyone's praise of this title. EuroVideo has done a wonderful job on this Blu-ray. The main menu (animated and in 3D) is nicely executed.
As others have noted, some of the footage is indescribably beautiful. I've been to the Grand Canyon a couple of times. The last time we went, we shot around 900 pictures, but not a single one could convey a fraction of the awe that one experiences when seeing it first-hand. This IMAX 3D footage (and the fly-overs in particular) comes the closest of any media I have ever seen to conveying some of that awe. The 3D helps to relate some of the vastness and scale that simply can't be captured in 2D.
I was surprised to see some decidedly 2D footage sprinkled throughout the feature (e.g. Tara's kayak adventure). I'm not sure whether these shots were intentionally shot flat or whether there was some technical glitch along the way.
Also, the two or three fisheye lens shots (which seem to be present in every IMAX documentary) look kind of odd to me and don't seem to work as well in 3D as they do in 2D.
I'm not trying to nitpick. To be fair, I am continually amazed at the places in which, and conditions under which, these filmmakers are able to get an IMAX 3D camera rig! And I'm certainly grateful that films like this are getting made at all. It must be a massive undertaking.