I've had the the Garmin Nuvi 250 for about a month now, and have used it several times in order to get a feel for how the device operates and how accurate it is for everyday navigation. So far, I have been very impressed with the ease of use of the device, and its navigation accuracy. Now don't get me wrong, the device has its bugs. For instance, I have not been able to get the device to map out a route to my father's residence. No matter how I select my dad's address, the Nuvi just hangs at 80% completion, and will not begin navigating. It's odd, and I've been able to get it to map a route to an address on a neighbouring street, and that seems just fine.
I've also used the device on foot for geocaching on several occasions, and have found that it was just as accurate, and more useful than my Garmin eTrex. I have been able to connect it to my wife's iMac without problem (it is recognized as an external drive) and it has been very simple to add waypoints using the computer instead of entering them manually into the device. The most pleasant surprise was to find that the Nuvi recharges when it is connected to a computer through USB. A truly useful feature. I have also been very impressed with some of the useful software utilities provided by Garmin. These tools can make route planning a little simpler, and uploading these routes to the device a piece of cake.
I will post more information on my experiences as I continue to use this fantastic gadget.