As long as you have fairly decent Verizon cellular coverage your good to go. You could even add an external omni or yagi antenna if you are in a fringe area.
The backup battery gives 36 hours standby and 3 hours talk time in event of power failure. You can even carry the small base unit with a corded phone and take calls around your property using the internal battery. It has an embedded GPS chip that's used to pinpoint your location for 911 calls. I'm not sure if you could travel with it, but in theory, I suppose you could.
So far, the call quality is excellent with no dropped calls. Being able to port your existing number is cool. We're getting one for my parents. They both have life alert pendants which are compatible with the unit. Even if you bought it and eventually didn't like it, you can sell it and get most of your money back.
I have other friends and family that are about to bite on one as well.