Garmin on Smartphones?

Hi Guys,

I've been looking at getting a new phone since i want to go over to a contract rather than vodafone PAYG. The Nokia Navigator took my interest however i was put off by the stupid costs to keep updating the GPS service.

My Dad has a Garmin nuvi something or other satnav in the car and it's fantastic. I know garmin software is available for some mobiles and so was just wondering what people thought of it? and what's it like compared to a proper satnav? Also, what phones is it available for?

Many thanks!