How's that working out for you?

I've written a similar (open-source) app called Remindly (https://github.com/nathanstitt/remindly) that uses region monitoring to fire alarms.

I've found it's region monitoring accuracy to be horrid - either the alarms fire when I haven't moved, don't fire at all, or fire an hour later when I'm 20 miles outside the region.

Since I have the same issues with the built-in Reminders app, I suspect it's something specific to my geographical area, or the api is just rubbish.