Just got back from a 250 mile roundtrip and thought I would give google navigation a go on my desire. I have to say it is fantastic. My desire picked up a GPs signal within seconds and I quickly input the post code and the route was calculated almost instantly. The voice navigation is clear and very detailed, not simply just turn left but more " turn left onto the A12 to colchester, chelmsford, London. It was very detailed and knew road names etc. Well impressed as it is free also, i did not notice that is used any data either maybe a couple of MB