Bing Maps for Windows Phone 7 is shaping up, but so far lacks voice directions0
In fact, the Bing Maps app being previewed isn't actually a final build, which should give some expected users the hopes about seeing voice guidance down the road. So far, the experience is looking to be pretty smooth as it takes advantage of the most common features found on other maps services – such as points of interests, directions, and various map views. And to top it off, the interface is running especially smooth which will naturally exemplify the overall fluid movement of the platform.
Still, there are some advantages that can be seen with Google's experience, such as voice navigation & street views, but with more work and practice, Bing Maps for Windows Phone 7 should prove to be a worthy opponent.