I love being able to see alternate routes and feel confident that I can always find my way. Moving every 3-4 years keeps me on my toes, and the GPS has revolutionized getting to know a new city. I'm not constantly lost at the beginning. Very nice!
I'll grant you, they do have their downsides. Sometimes roads are labeled wrong and new roads aren't added (at least not to mine--I need to get the updated CD, but the price is zaa-zaa-zing and not guaranteed to cover my area.) causing confusion. Sometimes its routing is not the most efficient way of getting places. There are even "unverified" areas that don't seem to compute and other areas where I end up driving roadless across the screen.
Whatever. I'll take it. Warts and all. It has made my life so much easier. It is a wonder.