If a girl works her pecs they build up under the breast and make them look fuller. And the boob-shrinking thing is dependent on what a girl eats. But to stay on point, I think that the yoda comment is a little off. Yoda and this are two wholly different concepts. Just because you can create something in high detail in 3DSM does not mean you are an artist. As much as the ability to make a high performace car makes you a master of automotive expression. The question is: do you make a Saab, or do you make a Ferrari? Just because you have the best paints does not mean you paint the best picture.
So as for the wallpaper, there are good things and bad things. First, I think that the background shapes are interesting, perhaps the texture or lighting needs work, but for now they serve a purpose. Your blending needs some work on Gwen herself. I think the fade on the thighs looks especially irregular. I personally don't mind the image overlap on her shoulder, but if you want to create the illusion of Gwen molding into the background, integrate her more. For example, you could match the curves up on her shoulder and head, like the hair on the Adobe Illustrator startup screen. It might also be interesting if her black clothing was saturated more by the background texture. The color would flow better. I also don't think that the type needs to be quite so big.
cuz she isnt pretty imo.