I like the larger piece at the bottom of your post. Much better than the cartoon work.
On the cartoon work:
My first reaction is that Disney is very aggressive about copyrights, so er, be careful.
The lines could be cleaner. Tinkerbell's wing, for example, is full of jaggies.
The extra pixels scattered here and there are noisy and detract from the images, I think.
Here is where I become a real Debbie Downer....
I think you're mixing the weakest parts of each style/media (flat cartoons and pixel art).
Flat cartoon art relies entirely on the line. Varying line thicknesses and smooth curves are used to suggest form and define the shapes. But low resolution pixel art doesn't have varying line thickness, and has only a limited ability to draw smooth curves.
Pixel art can use groups of pixels to convey shape, or shading, or form. Or the pixels can be used to suggest features and elements which are not actually present. I think that using flat, high-contrast colors explicitly bounded by an outline on all sides prevents you from using these strengths.
Sorry to be harsh, but this art ends up with the weaknesses of each, and the strengths of neither.
I suggest reworking the outlines. After cleaning up the jaggies, either adjust the outline colors to simulate varying line thicknesses, or remove the internal outlines altogether (or maybe both). Removing the internal lines yields more pixels to use for the shapes and with the high contrast colors they are not really needed.
Just my 2 cents, I'm often wrong.
Tourist