Hello. I like this, it's generally a good balance between detail work and vibrant cartoony-ness. However, here's some crits:
The highlight you've given the hair is plastic and 'dirty'. It doesn't complement the volume and texture of hair well. There's something really wrong going on with the colours there too. There's gray pixels that are almost interchangable with some yellow-ish tinted pixels, and generally much palette wastefulness. Hair is difficult to render properly, but a 'blob'ish highlight makes them look like they're wrapped in a thin layer of plastic.
The face is a pretty good render, I like the expression and mood. The tie seems a bit underdeveloped with just a dither. shoes, shirt, places where you use the hair colours all are executed 'dirty'. This is 31 colours, and it could probably be dropped to about 16 for no loss, if that's your thing.
Maybe the black outlines on the hands aren't needed, and shapes could be defined just as well with some buffered dark colours.
What is the green square behind him? It's underdeveloped to the point where I have to ask what it is.
