GPS Voice Navigation is a turn-by-turn navigation app for your Windows Phone and it recently received a hefty update. The version 5.1 update for Windows Phone 7.x devices gets a map autozoom and search in contacts feature along with a few bug fixes.
The version 6 update for Windows Phone 8 devices also adds the map autozoom and search in contacts features but also adds 2D/3D map modes, full voice directions, night mode and offline maps through Nokia Maps.
The offline maps is a nice feature that is accessible through GPS Voice Navigation's settings. Just choose Nokia Maps as your map provider and you then choose which maps to download. This is a great feature for those times you are traveling and drift into those dead zones where a wireless signal barely makes it to one bar.
All in all Melon Mobile has done a nice job updating and improving GPS Voice Navigation. There is a free trial version available to let you try things out and the full version of GPS Voice Navigation is currently running $6.99. You can find GPS Voice Navigation here in the Windows Phone Store.