Large Monitors Mean Less Interference
GPS monitors are easier to read, because they are larger, about 4.3 inches, compared to the 3.5 inch iPhone screen. When you change and need to look the way this can make all the difference.
Personal Navigation Devices (PNDs) are reliable; They can determine your position accurately about 15 feet. However, smartphones sometimes have a few blocks or lack of reception time to detect your location.
Smartphones often use weaker GPS receivers and CPUs that share the battery with other applications and slow them down. PNDs like Magellans are designed with only GPS in mind, so speed and resources are not compromised.
Smartphones Work On Functionality
Smartphones create all-in-one devices with Internet access, but voice guidance is interrupted when calls arrive, it's still a phone.
No Monthly Billing
When you buy GPS, you pay only once for your device, unlike the smartphone that takes money from your bank account every month.
PNDs are entering Smartphone Market
PND manufacturers appear in smartphone with devices like the Nuvifone by Garmin that combines GPS browsers with 3G phones. To refresh the GPS market, TomTom has also added celebrities like Darth Vader to blend.
It is clear that at least for now, smartphones can not be replaced by your truly dedicated PND. Standing simple GPS units are simply better than your smartphone competitors, as well as they do not send you an account every month.
Source by Andrew Eisner