I have the same navman as dennis .. Have had it for a week or so now .. I found it very accurate .. only time was when I went on the M7 and obviously its not on the maps yet .. Other than that I found it did give different routes when you calculate quickest v's shortest .. Havent driven trough the city yet with the GPS ... I m sure a booster antenna will help any gps with high buildings etc .. ebay has them for pretty cheap .. I chose this for the same reason as dennis .. its small, light and easy to use . (ultra portable) I generally connect and get a signal in 20 seconds or so Instructions are clear .. I know the tom tom has different accents .. eg pommy of american or even austin powers n other cool stuff you can download from the internet .. so if that appeals then maybe play around with the tom tom .. with the navman you either have the choice of a man or woman .. Thats about all I can say at the moment .. coz its only been a week or so