The driver found the system worked. Voice prompts would notify when approaching a turn and which direction to go. But lack of visual cues, either maps or text, could make things confusing. And if the driver misunderstood the directions and had to turn around, OnStar would notify them, for example, to turn 'south' and leave it to the driver to figure out where 'south' was.
General Motors, which owns OnStar, plans to roll out the Turn-by-Turn option for all its 2007 vehicles. Pricing has not been announced thought it's expected to match a similar feature available on cellphones.