I am using Photoshop for the NPR look, as follows:
1. Use Smart Blur to help flatten the details
2. Median Noise to make the shapes more 'roundy'
3. Make a copy of the layer, and use Find Edges. Desaturate and adjust brightness/contrast to make it darker. Set blending mode to Overlay.
4. Create a blank layer, and use the Texturizer to create a canvas texture. Again set the blending mode to overlay.
Thats the basics of it. I didn't create that technique though, I learned it from a tutorial.
I could probably create a similar effect using Cel Shaders, but I'm happy with what I've got going here.