it never constantly updates. on the maps app, it never keeps the dot updated. it just "jumps" from place to place. usually that's not a problem, but most of the time i'm on a curved road, the dot would keep going off the map. i bought the tomtom app expecting it to actually work like real gps. Tomtom as an app is really amazing. When I was on I-95 ( a straight highway), tomtom was very accurate. it calculated the speed precisely and updated well. when i went on another interstate that's shaped like a circle, it simply couldn't realize i was still on the highway. every second it would go off the road, or onto an exit. i'm not trying to criticize the iphone, just wondering if this is normal or should i get it replaced.