Some of the route planning on the n95 is a bit nuts, from m11 to ruislip, north west london it took me direct rather than via the m25, however to get to paddington station it was superb. It pays to have a rough idea where your going and leave it to do the tricky bits at the end lol!
Alternatively you can apparently add tom tom software to the phone, possibly slightly better than the in built nokia version.