Okay, I don't really do this but I'll try. I promise I'll go easy.
First off, I like how you posed Xemnas, makes him look like his controlling someone or something. Those white lines(or highlights) on Xemnas's cloak looks great. The chains on his chest should be slightly fixed. But if you think it's supposed to be like that, then it's the wind or something.
Second, you edited the background right? The heart shaped moon is actually a good choice. But why not choose KH? Just wondering. The only thing I recommend is the snow, I think a different brush would give it a great look. Or a snow texture. Also, see what will look like if you adjusted the brightness and contrast.
That's all I can say. You said it was crap. I think it looks great!! I think it's sort of a practice. No artist can call their art a crap. . . sometimes. . . XD
i agree with the snow. that was what i was going for but the blur of falling snow was distracting. so i used the add on for mmd called kirakira which is like ....you know the lights that fall at the end of kh1 when kairi is on the island? those kind of things
as for the kh moon ...i dont know i was going for monochrome so purple blue yellow and pink would have ruined that. but i tried to make a moon shape heart to compensate
thanks by the way!