It doesnt work at all for me. Maybe because I live outside of US or something else, but I would expect it to use only the maps and my location..
- downloaded maps for Netherlands (I live here)
- added my home, grocery store etc (She recognized all of them) to Places, but out of 6 times I have used the reminder (Cortana understood every reminder - What and Where), she never reminded me when I got to the place, where I should have been reminded in.
I would expect the assistant to remind me when I get to the place or, for example @Remind me to buy Vitamine C when I pass through/I am close to a farmacy@, SO before I get there or at least when I am near a pharmacy, Cortana to notify me. I guess she can use my location and calculate my speed and estimate that with the current speed and direction, after 2 mins I would get close enough to a pharmacy, so she can tell me..
I am not a programmer or developer, so I am not aware if this is possible at present time, but as 99% of mass consumers that would be one of the basic operations I would expect of a personal assistant to do for me.