I bought a 660 last year after a frustrating experience attempting to navigate Munich. I am far from an expert with the unit, but I have very mixed feelings about it.
Sure, it does what you'd think it should do, pretty well. But twice now I've been unable to plug in an address to it, because it doesn't think the street exists; except that later, I've found that the street is in its database. The last time, I was trying to find a friend's house outside of Merlin, OR (definitely the closest town to him). After not finding his street, I called him and he gave me directions, which I used to drive around on the screen, and sure enough, there was the street.
I find it pretty useless for finding nice little roads in an area I'm not familiar with. Neither of its two choices for choosing routes -- fastest time or shortest distance -- begins to do the job. And it has the same problem as all of the computer mapping software, you have to zoom in much too far to be able to see any road you'd actually enjoy riding. So, if you're visiting some unfamiliar area, you need to bring a map with you anyway.
When you're riding with the unit on, even if you're zoomed in, it often doesn't show the street names coming up. Or the freeway exit street names. Also, it seems to decide on showing different streets' names if you're in 2D mode vs. 3D mode. I went to a campout last fall, and remembered that there was country store a few miles further along the road I was on -- thought I'd get some libations for the evening. I drove the unit around (in 2D mode) and there was a likely looking intersection, but no street name, regardless of how zoomed in I was. I took a chance and rode there. As I'm coming up on this road, in 3D mode, sure enough, there's the street name I remembered.
So, I have very mixed feelings about these "farkles". I've had nothing but good experiences when I could type in an address, but otherwise I'm disappointed.
