Learn something every day. So for many purposes, it is no better than your cell phone?
Well, that's not exactly what the salesman told me, but that's what I am starting to understand

.
You can check out the
OnStar coverage map for specifics, although I am still somewhat confused what "Limited OnStar service available" really means; areas without cell service are shown as this limited category while very few areas are labelled as no service available.