As I am sure I among the last commentators, I won't belabour that i think this shot is too far from the subject and its very grainy without any artistic reason I can think of, and its out of focus. That said, I do like the capture of the rainbow and think you had a great idea here! :)
Potentially great shot, in my opinion... a couple of issues, though. Foreground is a bit dark overall, drawing attention away from the rainbow and subject. Issues with compression are a bit distracting, as well, perhaps because it is enlarged from a small section of a larger print? Focus seems a bit soft, too... perhaps because of the same issue.
I like the graininess of this shot, but I think its oversharpened a bit (evidenced by the white spots between the image and the border). Still, its a nice shot with good use of negative space