Tomtom's new device looks very much like its predecessors, but changes to its innards have made it easier to use.

We looked at two of its big brothers earlier in 2007 – the One XL and the Go 720, but this one is available for £125 online, meaning most drivers can afford one.

Like the more expensive Tomtom Go, it uses what's called Mapshare to ensure that the maps are continually improved: every user can make corrections and alterations to the maps using the touch sensitive screen, then when the Tomtom One is plugged into a PC and connected to the internet, the changes are uploaded for verification. At the same time, verified corrections made by other users can be downloaded.

The One includes a socket for an TMC antenna - with one of these attached, live traffic information is available, meaning you can plan routes to avoid jams and accidents. Even without this, it's possible to tell the device about known roadblocks located up to three miles ahead and it will find a way around them.

A power switch is the only physical control; everything else is done by tapping the screen. There are never more than six icons displayed, so hitting the right one isn't a problem, even for those with large fingers.

The main screen shows the route and details of the next turn, plus optional information such as speed. Directions are spoken by pleasant-sounding, clear voices that can be heard without difficulty.

For UK journeys, destinations can be entered as towns, postcodes, road crossings or house addresses. In emergencies you can choose to be directed to the nearest hospital or police station.

The pocket-sized One runs for two hours on its internal battery, which is useful if you want to find your way around city streets on foot. In the car it is powered and charged by plugging it into the cigarette lighter socket, and in the home by connecting it to the USB port of a computer. Leads for both purposes are provided, but there's no mains adapter, which could be awkward if you take it on holiday without a computer close by.

Vista compatible: Yes