Good things: The background is actually very well done, it fits the video for the song. The ruffles on the bottom of the dress, the cuffs/bracelets, the feathers, hair, and eyes are just oh so detailed, more than what I can do. You really know how to use photoshop tools (or tools in whatever photoshop-like program you used)

Only thing that bothers me is how thin she looks around the waist. She's very skinny, she almost looks unhealthy.
Maybe adding more onto her, the curve is nice, just don't dip in inward as much, and maybe that should do the trick.

Her arms are good sized comparing the sizes around the elbow, wrist, etc to eachother look fine, but to the body they're very thin. Same tip as before, don't be afraid to make things bigger, wider, etc.

All in all though, this was a nice picture to look at. Had to, and really did, look at everything. Her face, her hair, then the dress, and really looked at the background. I have nothing on the coloring job, it's fantastic in this.

5 stars for vision, because you seemed to have an absolute amazing idea for this.

4 stars for originality, only cause this is fanart.

4 stars for technique, you color well and obviously know how to use photoshop very well, but anatomy needs help (except the face)

4 stars for impact, I spent a good deal of time looking into the picture, at everything I could, and since it's also off a favorite song, and the contrast from the blue to the magenta/purple grabbed my attention.

Original.. Not very original since many artists have done fanart for this song already. The background was good for my first 10 second glance, but eventually it looked very cluttered and random to me.

The anatomy is a bit off even if you're trying to pull off the chibi-like style. Her arm is really skinny. It makes it look like she's anorexic especially the wrists, they look like they could snap off. Try making them a bit wider next time.
I really like the way you drew the hands though they turned out perfect.
There's something's really bothering about me from the position she's in.. is she slanted a bit? It looks like she's not standing straight since the left shoulder looks longer and her left breast is lower than the other, if its actually a slant instead of drawing error, try adding more shading on the right, it tells us that the left side of her body is facing towards us more.
The socks look like its stuck to her skin, try shade the skin the socks are on top of so it looks like they're socks and not tattoo's.

Some of the tips on the hair strands aren't colored but I understand if you're trying to make it look like there's light coming from everywhere, its a good effect but I think its better if you fully shaded it than leaving a job undone.

The headphones are a bit small compared to her head since it would look like it would fit someone who's smaller than her, try drawing them a bit bigger if you want to adjust the picture later.

Overall, the face and shading on everything else is fine.