For lordhamster, I'm using the Navigon app and am extremely pleased. I'm actually heavily invested in TT devices, my wife uses a 920, I have a 930 with traffic receiver, but if Navigon continues to support this app and perhaps add traffic I could see replacing my TT for this. However I don't use any navigation system on a daily basis, if I did I think my stand-alone device would be my choice, at least for now. But if I wind up traveling to other areas without my own car I'll only be taking my phone with this app and not a second device.
From what I've read on Navigon's site, they are promising TTS & Traffic later this summer. Which is a shame because I'd love to use TomTom for the IQRoutes... they really need to get their act together and release an improved version. For being the most expensive nav app on the market they are going to have to deliver some neat features.
no external device needed - it picks me up as well in my house as it does outside.
The 3g signal in my area, Baltimore, is quite good.