Satellite navigation, like most technology, is getting cheaper and cheaper – you can even pick up a Tomtom for little over £100 these days.

So at £400, the top-of-the-range Go 930 Traffic from the same company has to do quite a lot to justify its price.

There's plenty here, to be sure. In addition to the latest version of the navigation software, and the latest maps, it comes with some neat touches that show themselves while you're driving.

For instance, there's 'advanced lane guidance' which shows you which lane of dual-carriageways or larger roads you should be in – the display shows a number of arrows in the bottom-left of the screen, with some in white (to take) and others in grey (to avoid).

Then there's the traffic information – it comes with its own traffic aerial, and while we've previously been unimpressed with sat-nav traffic information, this time it was fast and accurate, and easy to use (it appears in a thin panel on the left of the screen).

The screen is well laid out and it's relatively easy to get back to the menus and set up routes, but we found it harder to plan a multi-stop route on this device than on, say, the Magellan Maestro 4200.

Then there's the FM transmitter, so you can hear the directions over your car stereo. The voices in the Go 930 are loud and clear, though, so it's not a big deal. It can link to your phone over Bluetooth for hands-free calling, too.

Then there's the new IQ Routes – Tomtom says that the device will take into account likely traffic conditions for your route (it has a database of average speeds) so that, for example, it won't route you down a rat-run at school-dropping-off time.

With maps for the UK, Europe and north America, the Go 930 Traffic contains almost everything you could want from a sat-nav, and it has a price to match. The question is whether any one person or family will use all the features. If you will, then it's absolutely the one to go for, but we reckon that most people will be better served by a cheaper system that does a bit less.