A proper paper diary is silent and unobtrusive in use; it has no batteries to go flat; it doesn’t break if you drop it or tread on it; it helps you remember things because you have actually written them down; you can write in it during meetings and so on (when your smart phone will be outside or turned off!); and things don’t get mysteriously deleted. There is the risk of losing your paper diary of course, and unlike a smart phone will not require a passcode, which is something to bear in mind.
When you are getting your next diary, planner or calander please choose a British made one. Before buying, check the inside or back cover and see where the diary you are looking at is actually made (printed and bound).