One of the constant feedback N's mandarin teacher give is he doesn't hold a pen well nor like to color. She adviced me let N practise more at home. Honestly, i feel that N will eventually come round to it when he's ready and there's no need to push him. That said, there's no harm in exposing him to handwriting related activities.
N has no interest in mindless coloring but would color if there's a concept for him to apply. That's why i bought this book so that N can do what he is interested in (apply the concepts he learnt) and unknowingly practise his coloring techniques.
As expected, N was very eager to do this and could have completed the book in a sitting (but i didn't allow that). I got him to read aloud and follow the instructions on each page. He did so independently with minimal help/explanation from me- except that i had to nag at him to finish coloring. His one hand was coloring a page but his eyes were on another! That's how much he likes to color!