I programmed in a route, my wife dropped me off at the start and I was off. (Garmin 800, so it does turn by turn directions).
I don't know why, but I stopped to look at the thing and make sure I was going the right way and for some reason it said "turn right here" even though I was supposed to turn another mile or two down the road. That's where the "fun" began! It was actually navigating me but not on a route I put in. I ended up doing about 2.5 miles on dirt/sandy roads... Dirt! Actually, dirt is fine but there was about a half inch of loose sand on some of the roads (Apple Valley is in the "high desert" and frankly, it was pretty deserty) 25mm tires on sand is not good. I'm happy to report my speedplay cleats took it all in stride, despite no shortage of putting my foot down in loose sand.
I guess the good news is the thing was still actually directing me, even though the directions were ********. I don't understand why it told me to turn off the road that I was supposed to be on and going straight.
Oh well. A bad day on a bike is still a pretty good day overall.