Just bought a Garmin 360. love it. With the state of most street signs--either illegible or missing--it's very nice to have a voice that tells you to "turn left onto Somethingorother in two-tenths of a mile".
While I find that the gadget's knowledge of my local roads isn't as good as mine (surprise!), and that it sometimes chooses routings that I normally wouldn't, it hasn't really steered me astray. When I choose to ignore its suggested route, is announces "recalculating" and picks a new route starting from whever I happen to be.
       Just got back from navigating around Ormstown, Quebec. Worked jes' fine, there, too.