If you live in the United States, try "Navigation" by GPS Tuner. It has voice turn-by-turn, and works great. It find locations faster than my dedicated Garmin GPS, and recalculated faster too. You can try it for free, or pay the $5. It's much better than paying a monthly fee or paying $30-$50. Frankly, this is one of the best apps I've purchased in any category.
The downloadable maps that come free/standard on the HTC 8x sounds cool, especially if you go somewhere with limited cell coverage or travel to Canada. And hopefully once Drive+ is out of beta, it will be available in the Windows Phone Marketplace. This way, HTC doesn't have to license anything since the user will get to make that choice. And if you want the old Bing Maps, there's a few apps in the marketplace that will open Bing maps with turn-by-turn (no voice).
Bottom line, voice turn-by-turn navigation functionality does indeed currently exist for all Windows Phone users. So that fact should not deter anyone from buying a Windows Phone.