I loved this very much when I first saw it actually. I am only writing this because you requested a critique otherwise I would go "Wow!" and leave it at that.
Vision: The futuristic vibe to the whole picture definitely caught my attention. The prevalence of white and the mist in the background gives it an ethereal look. The building structure was interesting but not overtly unusual. It is a very plausible setting. The whole picture draws me in, especially the way the path is curving around and leading into the city. It is basically suggesting a journey that the couple has to undertake which is very appealing.
Originality: The concept for an anime is interesting because it seems a cross between present day technology (eg. telephone wires) and future architectural design. Again, I think it is the appeal of the cross between fantasy and reality that is very pleasant to look at and very beautiful.
There were only two things I thought could be improved (in my opinion): 1. The formation of the clouds. Clouds never sit in clumps like that, it is kind of an odd way to depict clouds. 2. It is hard to tell what time of day it is from the dark blue sky and the white fluffy clouds. Then again, this could be deliberate.
Impact: Beautiful scenery, great composition, fascinating concept for a movie.