Once the route has been calculated, a map screen appears with a temporary inlay telling you the distance and time to the destination, and the most major road the route will be using. The initial map is merely two-dimensional, like the basic Google Maps, but once navigation begins this switches to the quasi three dimensions now familiar with most satellite navigation systems. A bar at the top of the screen provides details of the next turning, including its direction and distance, plus the name of the road. A smaller symbol beneath and to the right tells you the direction of the next turning after that, but provides no further information beyond this.
There is no fancy lane guidance graphic to tell you which carriageway to be in at complex junctions, but the top bar does at least tell you the motorway junction to look out for and which motorways will be signposted. The roundabout graphic also leaves a lot to be desired, as it doesn't illustrate which exit to take, instead just showing the turning as you get to it. Having missed numerous roundabout exits with other sat-navs that didn't update their map screens quickly enough, we suspect Google Maps Navigation will occasionally have you circumnavigating roundabouts a couple of times to ensure you get the right turning.
Along the bottom, your current road is shown on the right with the estimated journey time on the left. Clicking the latter calls up a map overview showing the whole journey. This will also display any traffic information along the way. However, this screen won't let you navigate around jams. For that, you will need to use your phone's menu button to call up Route Info. This displays the same graphic, but with some extra buttons for various functions. You can choose to avoid main roads or tolls. But there's also a button to calculate alternative routes. This provides two more options, which are ranged along the top of the map, with details of their length in terms of distance and duration. You can then click on the one you like the most, and then return to the turn-by-turn map screen to use the new route. However, as with the map data itself, traffic information comes via a mobile data link, so this needs to be operational on your phone to receive the information.
The map view will work in portrait or landscape modes, but only if your phone has an accelerometer. The G1 we were using for testing would only switch to landscape with the keyboard revealed, which is clearly not going to be compatible with a mobile phone screen mount, and there's no way of manually switching to landscape. It's also possible to call up a text-based list of the different turns, if you prefer that mode of navigation.