I've had a lot of positive results using a Garmin 800 for both preplanned routes and on-the-fly navigation, and in all three car/bike/pedestrian modes. The GPS gives me so many options to explore, or just get from A-to-B as quickly as possible, without the worry of ever getting lost ("lost" means not knowing where you are. with a GPS, that is impossible).

I have used this in N. America and many countries in Europe. Have a SD card loaded with 2 Garmin's City Navigator maps for N. America and Europe, plus for cycling I load OSM routable cycle maps on that same SD.

The 800 has been extremely useful in large cities providing turn by turn directions, etc. Not only do I use it while driving and cycling, but also on walking tours. This year we spent days walking all around Rome and Naples without a hitch. I tested my sense of direction in Rome and failed a couple times. Luckily we had the GPS to steer us back home.

While riding unknown roads, the GPS map acts as a "look ahead" so I can bomb descents quite quickly, knowing ahead of time when tight corners are coming up. When locals see you are at speed and competent, I have found they give more room and respect rather than treating you as a tourist getting in their way.

My #1 gripe is that the screen size is barely adequate for reading the map information. My eyesight is becoming more problematic in the last couple years and so I would really like a iPhone size display for my full-on bike/map GPS, but the new Garmin 1000 model is only marginally larger than the 800. The information available on the GPS is fine, it's just the map size/resolution that I'm finding problematic without reading glasses.