Theres 2 other annoyances with voice commands.
First, it waits 1-2 seconds before listening, this means i have to watch the screen so i can know when to talk, kind of kills the usefulness of it.
Second, even though it says listening, that doesn't mean that the voice navigation part shuts up. In fact i had to wait a couple of minutes to give a voice command because every time it listened, it was actually talking, and the listening would hear the navigation and try to interpret turn left in a quarter mile. So then it kept on asking me to try speaking again. Only to have the voice nav portion start talking again.