Many of us have paid over $300-$400 for standalone GPS systems for our vehicles. I'm a telecomm systems engineer and frequently travel to addresses I am not familiar with, either in or out of my home state. I require a GPS to actually help me navigate in unfamiliar territory with realtime voice guidance.
I have about 10 friends with iPhones and NONE of them use the maps application to try to navigate while driving. The GPS is slow to update, doesn't show you lane entry information, doesn't announce anything and takes your eyes off of the road which is extremely dangerous!!.
Every time a GPS application announcement is posted at Macrumors, Engadget or Gizmodo there is always someone piping up that they don't see what the big deal is, they just use Google Maps, etc.
Get a clue, Google Maps is not real time route guidance and I feel sorry for the people driving around peering at the screen trying to figure out where they are going without killing themselves or other drivers.