While it doesn't reinvent the wheel I think this game is truly fantastic and wonderful; the game exploration is very metroidvania-like, unlocking more areas as you proceed by getting more power ups and eventually leading up to a section of the game where you can just handle stuff with your own order.
The main gimmick, the drawing, is handled extremely well and it just works, it makes the puzzles very interesting and fresh and they're not overdone in any way, every new chapter will bring you new gimmicks and new puzzles and while colouring is not required at all unless for the puzzles it'll be hard to not colour the world to your own taste, whether because you want to or because you need to for the exploration.
The story is handled really well and it's pretty down to earth, there's no bigger plots or anything like that, it's just a very personal tale and I thought it was neat. The music is fantastic and Emi Evans sang the credits song so what more could you want?