One of the ways Nokia is trying to differentiate from competing Windows Phones is by software. Nokia Music with its Mix Radio is certainly an interesting app, but the most important has to be Nokia Drive with its voice guided turn-by-turn navigation. While it's still missing many of the features found in Nokia's Symbian version, we do have confirmation that the Windows Phone version will be updated with these missing features.
One of the most crucial missing features is the full offline routing. Currently the Nokia Drive found in Lumia smartphones is able to preload maps, but for the actual routing an internet connection is needed. This is a big no-no, especially when roaming. Fortunately, Simone writes in a Italian site dedicated for Lumia 800 testers that according to Team Nokia "Nokia Drive will receive an update which allows offline routing too, in the near future".
Source: Nokia Lumia Diaries