first of all, I think this looks great! the use of shading works really well, and so does the use of color.
for originality, I'd give it 4/5 because this is the first I've seen of this part of the movie, in fan art anyway.
I think the backround looks great, the different colors on the mountain work well.
This could be a little better, though. you could have done a little more shading so we can tell which way the light's coming from, but then again that's done pretty well too.
overall, it's a great piece of art, although I feel like the contrast of some of the colors could have been handled better.