This is a neat idea. I like the minimal structure of the page and format. You can decide how you want to enter your appointments and to-do’s into the loose and simplistic structure. And yet, it still provides you with enough structure to think accordingly.
But … one must ask, why don’t I just buy a cheap plain/blank notebook and draw in my own sundial?
Muji also has a version, check it out here: http://www.muji.us/store/stationery/schedulers/chronotebook-am-pm-scheduler.html
What is your favorite type of planner or agenda notebook?