Well since we have AT&T and google pulls their maps from the net, no data, no map. Tom Tom has the maps in the app, it's a pretty big app, but my 32GB of storage can handle it. So I don't need to rely on a data connection for a map. Might not be important to verizon peeps. Although I found out today that I can talk on the phone at the same time the navi is going, I didn't think that could happen, but all you have to do once you answer a call is hit the home button and then start the app again.
Very happy with this app.