I like the whole series of images but the first one IMO is the best,it was the most pure to the concept(the stark beauty of a lone tree in snow).This image,again my opinion,is still good-with the slight hint of clouds in the sky and footprints probably being more visible in the print so I can't say whether it makes it stronger or not.
In any event a fine image.
I like the image, but there's one thing that bugs me - the tree is placed *exactly* on the 1/3 horizontal and vertical point. While that may have been accidental, it looks a bit too much like 'formula' photography to me. That said, I'm not sure if you could have place the tree anywhere else...so perhaps it works in this image.
I agree with Peter - the right side needs a slight amount of burning to balance the image. Top/bottom tonal imbalances usually work, but left/right ones rarely do.