I'm curious how well it works myself. I've been with other folks on two occasions where their NAV system were less than helpful. In both cases they relied on the NAV (no maps). First time,it was on the way to the "Tail of the Dragon" in TN/NC, from PA. I knew the way but followed after we left the route I knew to take until he gave up in a parking lot a few miles from where we should have been. I led us back to the route and the rest of the way. The 2nd time was a trip from NJ back to PA - we were going to take a different route on the return trip. But they messed up somehow with either reading the NAV or feeding it the route - but we ended up dozens of miles away from the intended route before they realized we weren't where we should be.
My point is simply this: print or buy a map of your route before you make the trip, review it so you know approximately what roads to take, how many miles from each turn or road to the next, etc. IF the NAV takes over and gets you from point A to point B with no errors - great. If you get pointed to or end up on a dirt road in "Timbukto" and the NAV can't get you turned around - get the maps out.
All that said - has anyone here had experience with the voice commands and response and accuracy of a Honda OEM NAV system? I believe I'd prefer to invest in an after-market unit that I use in our van or any other vehicle I might drive (particularly if it will work in Europe).