If you're looking for a good GPS which uses TomTom maps, then have you had a look at Sygic? As far as I remember seeing, it is supposed to use TomTom maps. The interface is hardware graphics accelerated, has automatic traffic updating and rerouting, and as a bonus is the only GPS app I can find which actually tells me if there is a toll on the route and if I want to avoid it or not (configurable) when calculating the route.
Damn, that sounds like a sales pitch.
But in all honesty, I'm extremely happy with it, of course it does have some points against it compared to other GPS apps, but this is the only one I found that meets my requirements.