It got rejected hahaha! Any comments? Here's the link: http://www.animepaper.net/gallery/wallpapers/sessions/item69048/

Well, first, maybe it's just me, but it's a bit distorted, did you mantain the proportions when you resized the characters? I'm not familiar with this series so maybe it's the style.
Now for actual problems...
You used an actual scan as background, you should have at least extracted the character and design a background by yourself. Characters use up too much space as well. I'm guessing this is the scan you used.
There's a difference in the quality of the character images. The guy's colors are a bit more desaturated and grainy than the girl's. I think this is because the girl seems to be a vector, while the guy is a scan. I suggest you find a scan of the girl to make them both of equal quality (I guess it's easier than finding a vector for the guy), and apply cleaning. There's a tutorial I always link to, but now the site's down so it's like this:
1. Duplicate the layer.
2. Apply Filter>Noise>Median to the layer above
3. Set the blending mode of the layer above to overlay or multiply.
And as personal taste comment, text is... errr ugly. You might want a second opinion because I don't like text in walls, but you should at least try to not cover the characters with text.
The extraction you did at the little piece of cloth in front of the girl seems ok though, so I'd encourage you to go actually extract the characters.
Hope that helps, good luck =)