Detail was really paid attention to in this piece. The stitching of the dress, the folds of the fabric, the two souses of light. The only thing that really stands out to me that needs a little work is the eyes and the windows.
The eyes only need work, in my opinion, because of the rings. They seem hard, almost like they were filled in with a gradient creator. They really draw your attention, but I think the same thing would've been achieved with just those two colors because that electric blue really draws attention to the otherwise monotone-looking picture. (Not saying that it is void of color, just that the other colors don't really pop from each other, which is why the shading was so important to prevent it from being flat.) Otherwise, I do like the style of the eyes, going from as dark as the eyelashes, to really light at the bottom, even if you do loose the eyelashes a little bit where the color of the eye meets them.
A style choice that bugs me is the eyebrows, but that really is a style choice, so I won't spend time on it, other than just this.
The window is a little confusing. The way the curtains are makes the window seem a lot closer to her head than the size of the windows imply, which is all fine and well with the perspective that you don't really notice it until you look closer, but how the curtains go over the pillow suggests that it is a small window only the size of her head wide. - and the bars that go across the window, they usually don't blend right into the wall or the rest of the window, even if they are the same color. A small line, even if it's the tiniest that you can mange should help give depth to the window that you cant' quite achieve with the lighting.
The one thing I just don't really understand is the string... it's cute, but it took me a minute or two to connect the string by her feet to the string on her finger. I don't really have a complaint against it, I just figured I'd point it out. It's a really nice little bright spot to the picture, kinda like the eyes. It breaks things up a little bit and gives your eyes something else to look at and think about. It draws attention to itself against the otherwise gray bed.
Other than that, great job, great shading, the anatomy is really good as far as I can tell (near perfect enough that nothing stands out to me) By the way, the bows are nice touches, just wish I could see the detail, the shading makes them blend together in a smaller view.