I had one previous experience with this handy little device on the road trip to Comic Con 2012 in NYC. The bright, shiny new system has improvements I find both impressive and helpful.
The Garmin system provides owners with directions to wherever they choose to go. It locates you via satellite (or so is my limited understanding of the technology ... heck, like a computer, I don't have to understand how it works to make use of it), provides directions to the place you've informed it you want to go, and then directs you there verbally, with pictorial maps, and with written directions, all at once. In this way, it speaks to people who are learn best in a variety of ways.
What impresses me most is that when you are coming up on a complicated lane split, a small screen in the upper left uses arrows to show the lane split. The arrows in white indicate which lanes you want to take, whether they are on the left or right, and shows you the lanes you should avoid in gray. But that's not nearly enough. It also splits the main screen which shows you your car and the road ahead with your chosen route highlighted in purple (the interchanges where you need to turn show up as white arrows ... also useful), showing the map on the left and an image of what you will be seeing on the right, showing the road ahead with a red arrow on the lane you want to take. Exit signs are also shown. It's a confidence building feature.
In the lower right is a feature I hadn't seen on the previous version at all. There is posted the speed limit for the road you are traveling on (although some back roads and access ramps do not have this information available) ... and your current speed (shown in red when you are being naughty). This is a convenient little heads up feature that keeps your eyes on the road ... or close to it.
With various ways to input the location you choose to reach, you can navigate to private homes, public spaces, famous places, and local shops. The routes provided appear to be the shortest on first pick. They tend also to be the routes the locals use, so you gain a certain local street savvy just by plugging the Garmin in and following its guidance.
One upgrade I appreciate is that the Garmin I have does not bother telling you it is "recalculating" if you get off its suggested route. It simply adjusts to your new direction and provides updated directions almost immediately.
All in all, Garmin proves to be a valuable tool. It also gets you where you are going with both confidence and a wonderful calm (once you learn to trust it) that one can't get glancing back and forth between scribbled directions and the road or an atlas and the road. The only thing to watch out for is that you don't spend more time watching the brightly lit, easily read map than you do the actual road and the traffic Garmin isn't designed to report to you.
This is a system they never discussed in the science fiction of my youth. There were smart cars that drove you where you wanted to go, high speed moving walkways, ... and transporters of course, but nothing quite like this.