GPS is only a tool for navigation. It will *probably* help you find a route, but ultimately it is your responsibility as a driver to use what it tells you safety and effectively. If your SatNav tells you to go down a remote mountain logging road during a snowstorm, you should probably not do that. Likewise, the smart traveler should probably decide on his/her route prior to getting in the car so that you don't have any nasty surprises. Even the crappiest SatNav or phone navigation program puts a lot of information at your fingertips, so by all means use them. Just use them with a grain of salt.
Now for my rant. I have a Tom Tom OneXL, and while I initially liked it, the more I use it the more I find in inadequate. Both the unit itself and the maps. While my map update is admittedly more than a year old, it frequently misses "new" roads that have been in place for 5-10 years. This is annoying but understandable. I was sold a product that was incomplete. Nothing new from technology companies :)
But what really bugs me is the TomTom One's poor GUI (map navigation is a nightmare and you can't set the zoom level while in 2-D mode) and terrible route time estimation. I travel a lot (both work and to visit far flung families and friends) and so spend a lot of time in the car. There have been several times when I have let my TomTom talk me into questionable routing that cost me many miles and not a few hours. That is because it has really, really bad route estimation settings that you can't change in the head unit. It normally doubles estimate vs. the actual time for 2 lane/rural travel and will therefore drive you WAY out of you way to use the interstate rather than just drive a more direct route. I don't know how many times more that this will happen before I can no longer restrain the urge to disassemble it into the finest pieces with a hammer and mail it back to TomTom in a shoebox. But I already have the note planned: "Dear TomTom. This is not a warranty issue ..."