While it mostly gets local use around town I do sometimes take it across country with excellent results. Even driving through the mountains of west virginia it's working 98% of the time. Where I am right now I have 80ms latency which is about as good as it gets. Normally I would expect around 60-200ms latency (wiht a perfect signal) and of course when you are in a bad area 600+ and packet loss is to be expected. If you are unlucky enough to be in a bad spot you are pretty much always within a mile of a spot that you can get enough connection to send/receive email.
BTW - If you haven't had the pleasure of dealing with tech support I have contacted them for several reasons and always get to talk to someone right away.