Also I have been comparing the Droids navigation to a Garmin 765T (Borrowed) and my Mio c520 side by side. The Mio c520 is always on my dash and I will say the if the Droid's GPS had a night mode where the background is black it would be my only in car GPS.
The Garmin and Mio seem to be haphazard routing wise in comparison.
It's also nice not to have to worry about remembering to check for and load map updates.
One trip was a 240 mile round trip that took me through Atlanta both ways and the Traffic layer was uncannily accurate. The distance to turn was more accurate on the Droid.
I use a visor mounted Motorola T-505 bluetooth unit to get the voice closer to my head.