Originally Posted by Smiley90

Worked fine on my iphone in Hawaii, had data turned off as I'm Canadian, downloaded the route I had to drive via wifi in the hotel, then as we were driving my SO was looking at the GPS tracker signal in google maps and told me where to turn. It lags a bit, bit not more than like 100m at most. Worked fine. Accurate in a city as long as you're not speeding, we also used it in San Francisco as we were walking/biking.