If you look at the first line of the StreetDeck page....
"StreetDeck is more then just GPS NAVIGATION software"
The sound is just as good as it was before. Still beats stock sound hands down. I never really noticed that big of a difference myself, but I drive a shoebox, so maybe there is. But the new navigation.......first time I have totally trusted a nav engine in a very long time.
The best part of the navigation being built in? Startup times. Because it is no longer a third party that has to initialize by itself (does it in the background), StreetDeck can go from splash to cash (start screen to music playing) in 2-3 seconds. I also don't see the hangups on cold boots or coming out of hibernation. CPU usage is WAY down too.
For an audiophile, maybe centrafuse is the best choice. And maybe it is worth the price tag. But for the frequent traveler, StreetDeck is going to be a phenomenal choice at an outstanding price. When you think about the price of Mappoint, iGuidance, Streets and Trips, Centrafuse w/navigation, or any of the others, compared to $99 for StreetDeck? And then add the capabilities of StreetDeck (music, satellite, dvd, radio, etc), I think StreetDeck is finally safe.