I do both.
I keep a wall calendar in the kitchen (so it's handy for everyone) and I keep a monthly at-a-glance calendar on my desk (for me, to write things WAY in advance and scheduling purposes).
But I also use my iCalendar in my phone. I don't am not someone who schedules things daily, so it still works ok for me this way. About once a week I go through my ical/phone app and write things in my desk calendar. And by the week, I tend to write things on the wall calendar (b/c by the time *this* week rolls around, I pretty much already know everywhere I'm supposed to be and what's going on already, and I do it from memory).
My phone goes with me everywhere. So when I'm at the dentist I can schedule my next appt (and the kids' appts) right there. Same with oil changes. Or eye appts. Or dinner dates with friends. The rest tend to be more recurring items, like music lessons for my kids, or band practice, or book club, or volunteer events at church (food bank). So I program those in my ical on a repeating schedule (every week, annually, whatever). And then when I'm making that dentist appt, I can say, "sorry, no, she has band practice that afternoon, what about the following Tuesday?"
It isn't perfect. But, the more I do it, the more I am finding myself checking my phone's notifications (pull down menu, at a glance for the day) early each day, or late at night to see what tomorrow holds.
Car repairs for the son's car and pick up/drop offs for him to arrange it, deadlines for paying for/scheduling things (senior pictures, spirit wear orders, etc) are much easier to put into the electronic calendar for me. I can mark it for every day if I want, or only days when I think I might be able to do it, and then instantly delete it forever after once it's accomplished. So no cluttered up calendar with strike-outs all over it.
Or highlighted days at a time, when family is visiting the area.
Maybe one day I'll change over completely. But I don't expect it will happen any time soon.