I like the lineart, I like the composition, but the shading is really not well thought out.
Things are made of different materials, and here it looks as if all of the materials are the same be it skin, hair or clothing. Think about the texture of your materials and how it should be shaded like. The way the darker parts transition from the normal brightness is lacking because on different textures the transitions look different. On the shoes you do draw in the glossiness of the shoes near the highlights correctly so you have some understanding of different materials, but there's no difference in clothes versus skin versus hair. You do add details like clothing creases, but you don't shade them correctly to make them pop out from the canvas.
It should pop out as a 3d thing despite it being a stylized 2d drawing. As I said, I think your lineart and composition are great, but the shading needs a lot of work.