As a Kingdom Hearts fan and a pianist, I heartily approve of this cover. Well played.
My only pickle with this would be: Add a little bit of rubato where the theme takes a slight pause. It'll give more body, more expression to this piece. Not that this piece doesn't have expression already, but it'll add more oomph to what is already there.
Also, it's not that NG isn't big on piano covers because I know of a few people who do make piano covers (I did upload a live piano work on NG some time back and it was fairly well received). But I would love to hear... not a standard take on Namine's theme, but *your* take on Namine's theme. Can you vary it, for example? Can you make that cover *your own*? Covers are accepted on places like OCRemix on the grounds that the people making those covers put their own spin on video game themes. And judging from how well you played, I believe you can too.