The scene and the subtle HDR processing are stunning. Please forgive the following suggestion, though: for me, having the sun roughly halfway on the vertical dimension draws my attention to it at the expense of the fantastic light and shadow interplay of the forest floor. Again, for me, the sky and upper half of the image is kind of bland but takes up a tremendous percentage of the image. I would crop at the top of the starburst, which would put the emphasis on the luxuriant lighting at the lower levels of the image.
The problem with panos, vertical or horizontal, is that it is very difficult to find compelling composition across the breadth (or, in this case, height) of the image.
I wish I had taken it, though...