The use TomTom has for me during my trip is more routing options. On days I have more riding time to get to my destination, I flip it to "winding roads" mode. This also exposes the benefit of offline modes, as a lot of these winding routes have been in very limited cell reception areas.

Google Navigate (and iOS 6's navigation) offer best time routing only, with usually one or two slight alternate routes. For road trips, this means boring, but fast interstates. Not the greatest when on a two wheeled adventure

I'm not thrilled with the TomTom interface, but the data and routing has been solid so far. Prior to using smartphones for navigation, I used Garmin products in the past.