I must agree. I do not remember a very pleasant experience using the GPS dash units. I would move often with the Navy and would use the GPS unit for a couple weeks but challenge myself as soon as possible to learn to get around without it. Now when I am going somewhere over 30 minutes away I throw it into GMaps even if I know how to get there, as there could be a number of events that could've caused a reroute since the last time I took that route.
My commute to work is very predictable, but the commute home is not. I always use Google maps driving home, even though it is only 27 miles, because Gmaps will direct me to alternate routes if there is a traffic tie up on my usual route home. This has saved me literally days of time over my years of commuting.