Finally, after nearly two years, a developer has released the first real-time, turn-by-turn navigation application for the iPhone. XROADS G-Map ($19) is clearly the best real-time navigation option for an iPhone right now, but we ran it through the same tests we would a stand-alone TomTom, Garmin or Mio system to see how it fared with the big boys of navigation.
Their review scores the application using 10 different criteria for a max total of 100 points. All in all the app did well scoring 80 out of 100. You can get detailed information on its strengths and weaknesses using the link below.