This is wonderfully smooth. Great pose, great details, great colors. The palette is huge though! There looks to be a lot of room to reduce the palette without noticeably losing detail or smoothness.
I don't know the anime or manga that this character's from, but on a pixel-art level, it's excellently drawn. Very nice pose and colors. I feel like maybe her left ankle (our right) is a bit too thin. Otherwise, sweet job!
Three years later, I still come back to this for inspiration. I love these colors and the internal AA.