How Useful Is The Fm Traffic Feature In Garmin Gps Units?

I’m debating between buying the Nuvi 750 and the Nuvi 760. The 760 includes FM traffic. Is this just a gimmick, or does it work really well and is useful?
If my location matters, I live in the suburbs of a major U.S. city, and spend a lot of time in the city itself.
Thanks!