This is a very well drawn piece! I love the colour composition on SeeU's outfit, and even though I don't overly like the character I find myself drawn to it. The background is minimal, however in this it simply helps draw the character into greater focus.
There are a few things I have noticed that could possibly be improved on, however. First, her right hand looks a little strange. My advice would be to draw some detail on the palm, even just a small curve where the thumb connects. It'll help the hand to look more real, and less flat.
Another thing is the eyes. I absolutely love the colours and shading, but why the white star thing? To me, it doesn't look right. I know it's small, but I thought I should point it out.
Overall, this is a very nice fanart of SeeU. With a bit of revision, I can see this being something even more amazing.
I think the hair is lovely! Very nice shading in it Her face turned out very adorable as well! And the shading on the clothes is also well done. ^^ The proportions seem pretty well over all - just a few minor mistakes! Like Kels pointed out: the hand seems a little strange. ><
Btw - does she have such a flat chest? I don't recall seeing her so flat before O.O