That's a really good point there actually... when you're stationary it makes very little practical difference - but when you're moving - even at 40mph it makes a massive difference - especially when coming up to complicated road-layouts and the device understanding where you are on that system and importantly how high you are so it understands if you're going under something, over it, or just to the left of it.

Smartphones get around this like the old GPS units did by 'locking' the path to a defined road - when you leave that road, or you hit a complex layout or the signal drops to just 4 satellites then you get very confusing directions and quite often wrong directions as the device mis-understands where you are.

Signal is an important thing as well. Smartphones have single small antennae that are combined with their GPRS/GSM antennae - these have significantly lower gain than the dedicated GPS devices which have the tech required to capture as many sats as possible and move between them at speed. To deal with the speed issue your phone will use it's GSM connection to determine where you are based on near-by cell towers, but as soon as you turn that off (say because you're in another country and don't want the roaming costs) you'll notice how long it takes to find a signal - this is also an issue around high buildings and even mountain passes - where your smart phone may struggle, your GPS will work.

Garmin software is a bitch by the way - hate it - so hard to use and takes so long to learn. Tom Tom software is very very good and very easy to understand but doesn't allow as much flexibility in terms of using free maps and data.

Here's a review I did of the Tom Tom Rider

TomTom Rider Review | The London Biker

and here's a quick comparison I did with the Garmin and Tom Tom when the Zumo first came out..

Garmin Zumo – Initial Review | The London Biker

It's fair to say that over the last two years I've had the Zumo my opinion has changed.

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