Very cool and simple, however it feels a bit finnicky with the banding texture. I tried splitting half and half into black shadows and white hightlights and depending on the distance from the object some artifcats show up like this: https://i1.someimage.com/mM51rMg.png
would love to see how you solved it in materials tho. We use a toon shader on our characters in our game, currently the build for 4.10 made by another member of this forum (I forget his name atm!)