Tom Tom arguably kicked off the recent trend for all-in-one GPS units with the Tom Tom Go, based on its PDA software; it wasn’t the first, but it was a lot more attractive than some of the other options. The One is the latest version and has just one button – a power switch on the top.

Everything else is done via a touchscreen; and where others fail to grasp the ergonomics, Tom Tom’s experience pays off.

The reasonable size on-screen buttons are straightforward and easy to use, though the on-screen keyboard is best suited to those with small fingers, and there’s no stylus supplied.

Routing is quick and re-routing is fast too, without too many annoying requests for U-turns. While driving, the display is clear, with the top left and right corners being used for zoom controls, while tapping elsewhere brings up a screen of big icons – no fiddly things to tap on here.

The speech is clear and loud, and you can even link the volume to the car speed, which is a unique and very sensible idea.

The One also has Bluetooth built in, so the unit can use your mobile phone to fetch traffic information and weather data from the Internet; there are even different voices you can download.

But you have to pay a subscription for these, so factor in another £40 per year, plus any mobile data charges.

There’s a good built-in demo tour which will help you get to grips with the system quickly; our only tiny niggles are one blocked road that wasn’t on the map, plus the way you’re returned straight to the map after changing any preferences rather than being allowed to choose when to return.

When it comes to ease of use, and a well thought-out design, the Tom Tom One knocks out most of the competition and shows that there is more to satellite navigation than just repackaging a Pocket PC with some different buttons.

This article is part of a group test of satellite navigation systems. Others are:
Intro and Editor's choice
Blue Media BM6380GPS
Evesham Nav-Cam 7000
Garmin Street Pilot i3
Magellan Roadmate 300
Medion Go Pal PNA350
Mio 268+
Navman ICN520
Novogo A30
Tom Tom One
Viamichelin X930
Top-of-the-range options
The choice between all-in-ones or PDA add-ons
Europe's GPS constellation