I didn't think to check that but as it turns out my data billing cycle re-started on Monday and when I checked this morning I was only at 11MB so it's doesn't look like it was too bad considering I had been doing other stuff on the phone.
One thing that I love on my Smartphone is the ability to have the whole North American map on my smartphone. With the built-in GPS and my Garmin GPS navigation software, I am pretty much self sufficient for navigation. No data consumption required to be downloaded. Less battery consumption as well as its not needing to download maps to update each time.