Robert,
You've got some very strong compositional elements coming together in this image,and the sharpness is outstanding. What I would point out is that the lone, tall tree on the left almost disappears 3/4 of the way up its trunk. As a result, it doesn't quite work as an anchor. Moving slightly to ensure that the entire tree remained visible would have strengthened this image immeasurably.
Cheers,
David
Nice use of an s-curve here as a leading line to guide the viewer through the image which to me is your stronger compositional element in the image. Though I understand David's comment, I don't feel it is a negative.
I think it is a great composition, with the curve of the river leading your eye, and the tree framing the curve, defining it where the steam obscures it. I really like the high angle above the scene, gives a good sense of the scale of the place, and makes me really want to get back out there :)
Gorgeous image Robert; the snow really helps highlight the wonderful color of the canyon. I have an image similar to this (without the snow unfortunately) and I agree that sometime simplicity in an image (e.g., leaving out the iconic part you might be tempted to include) can yield as equally impressive results.