GPS on my travel

My Nokia N79 has a built in map with GPS device (through GPRS)... I have tested it many times from NST to Thung Song and it has never been more than 10 M away... In December I had to go to Surat Thani and I used it then too (not getting there but finding what I was looking for)... I can search for sights, public offices, schools, streets, special places of interest, temples and so on... I can also do a free text search and several alternatives will come up...I have never really thought much about this feature before I went to Bangkok with my students last weekend... The bus driver got lost several times, I was sitting upstairs watching the GPS and I could see he was lost... My phone was brillinant, stay in left lane, center lane, stay right, all commands were clear and very very easy to follow... When we went off course, it was quick to calculate another route for me... I wonder why I would have to buy a new GPS with a 7" screen for my car when I have this phone? I usually do not need technology to help me find the way but I have to say that when I go to Bangkok this vacation, I will surly use it... It was brilliant...Has anyone else used their Nokia maps/ mobile phones with GPS? Cost, 20 hours of internet = 100B