It's extremely accurate that's for sure. The only downside is that it does require a laptop to run. It's not really efficient for smaller trips.

I just purchased this. (Mio C310X). It comes with preloaded maps (as recent as November 2006) and is quite handy.

+ small
+ no fees
+ STRONG car kit (good mounting hardware)
+ SD slot for MP3 / video (requires an exe mod) playback
+ multiple "transportation" methods.

So if you're on foot in a strange city, it'll adjust for that. If you're on a bike, same. It's quite versitile.