I'm forever searching trying new stuff because I'm ... well ... and old geek. Here is a few alternative GPS applications (turn by turn with voice) I'm currently trying out. These are not the free GPS applications but they do provide a free trial.

Wayfinder 7
Garmin Mobile
Telmap Navigator

All of these are working with my 8300 Curve and the G-Sat GPS receiver. Give them a try, most of them are equal or better than Mapquest Mobile. I'm trying these out so I can make a decision to have a second navigator in case Telenav isn't connecting (yes this has happened, usually in the middle of a route) or gives me bad information (dead end streets or closed roads due to construction etc.). I travel every day because I cover about a 100 mile radius around my city and have roughly 279 customers to take care of and sometimes even though I know where I'm going it makes a good companion and it reminds me of home to have a female telling me "where to go".