My friend has what appears to be the same or very similar version (UK not USA though, obviously). It is pretty good, got us out of Silverstone when we couldn't and found the hotel around a bizarre one way system that would have given us hours of hell.
My friend has only had trouble with it on housing estates, where there are many turns in a short space of time, at which point it struggles to keep up and just confuses the driver. Other than that though, he hasn't had any complaints.
Hmm... It's starting to sound better. I got lost going to the warehouse club on Sunday. Google Maps said it was 20 minutes away. Why then did it take me 2 hours?
I've actually found that a current copy of M$'s Streets & Trips works well. I use it for finding customer sites, and when I travel. You can even buy a version with a USB GPS module that you can stick to your windshield, although I keep forgetting to bring the GPS when I travel.
