I like the photo, the lighting could have been better, but I think it still works like this. I think that you should have placed your arm so that it wasn't in the shot. You should have also strained your hand so that it looked like you were trying to hold yourself from falling of the edge. But, overall I do like the photo, and think your take on the theme is interesting, and from what I've seen of other entries, original.
I like this idea for the challenge, but I think I would have changed the composition some. If the person was really hanging on, the arm wouldn't be out like that. I would have tried for a little different angle I think. Anyway, this is pretty good and an excellent idea.
if the hand would have been straight on (as oppsoed to seeing your sleve) this would be more striking. Also a good shot for earth ;) Do like this though.
looks funny to me, although it might be done with a different message in mind. i think, it would be better if the arm wasn't visible. liked it, anyway.
where is the hills and stuff in the background. it would be great to feel as though you are really high, on a cliff or something. there is no tention in the fingure muscles, but i get what you are try to do.