The issue I've seen with the reminders geofencing tends to be a difference in where the phone is told an address is (usually via Google Maps) vs where the actual address is. I need a way to override where "home" and "work" is, without having to change each individual reminder.
It's not terrible for where I'm at currently, but could see this as a real issue for some other properties. An apartment complex in Austin for example that has their front gate marked as the address, when all the apartments at the location are .5 miles up a private driveway.
Overall though, I've been quite happy with geofencing, (a feature a friend had on an old Symbian phone cira ~2003), and am glad to see it more widely adopted.