LOL Margret does get a bit snippy if I ignore her. She has a delicious, long-suffering, exasperated quality to her voice as she says "recalculating".
Honestly I use her for everything, even trips for which I absolutely DO NOT need directions (like going from home to work or visa versa - it's only two miles away and I do it about four times a day 5 days a week). I mainly do this because she calculates my estimated time of arrival. I love this feature. It's also nice because sometimes I do zone out so it is nice to have someone say "Turn Left in 500 ft" even if I do know I need to do that, it gives me a heads up.
I also enjoy bitching back at her
Last year when I first got her I was in the car on the phone with a friend who was unaware of Margret's existence. Margret started getting loud and insistent about something or other and it was irritating me, so I blurted out in a very frustrated, angry voice, "Shut up, Margret! I'm trying to talk!".
To my friend it just sounded like a muffled voice in the background and then me snapping very angrily and rudely. So she awkwardly offered, "I can call you back later if now isn't a good time"