Holy shit...look at those...
Kinda cool that I sort of caused a spin-off, but anyways, as for the overall piece... I think it could definately benefit from more colors. The dithering is looking a little dodgy right now, not really too smooth looking. Also, in the picture, her face is looking more downward, but in yours she's looking straight forward-ish.
There's more when it comes to reference-to-pixel, but I'm afraid someone is gonna look over and see me staring at a picture of a girl with absurdly large breasts.