I agree. The portrait orientation draws you in and makse you travel through the landscape, whereas, I think the landscape orientation gives you more of an observer's view due to more of the surroundings being shown in the frame. Both great shots though.
Lovely and vivid. To me, the image should be cropped such that the stream starts from the lower left corner. The ice at the bottom is not necessary, I think, and the image is quite distorted there anyway. But a really awesome capture, nonetheless!