I made this today after getting a good feel for gimp. Ignore the white lines on the top & side, those shouldn't be there. I know it's sucky, but all I want is constructive critisism on how to improve.
Honestly, not bad for a first sig. The effect behind Sora is interesting, but it looks like you just slapped him in front of it without making Sora really part of the sig at all. The background itself isn't terrible either, interesting smudging work. Text could use A LOT of work though. I'd suggest looking up some tutorials, or using some of the rather nice ones we have here in the tutorials section. Not bad for a first go; I hope you keep at this.