There are many apps out there that can help with planning on your iPad. For some folks, they might be a good fit! But using our pdf file has several advantages:
Portability: pdf is a standard format (the "p" literally stands for "portable"!), so you can easily move the planner to a different notetaking app or tablet later on
Privacy: You completely own and control your notes, not some third party. Sync them automatically with iCloud, or however you wish
Backup: Your notes are saved in the pdf for posterity and can be viewed on any device