Pros: I love the Audible book feature.The maps are easy to follow. The navigation around the unit itself is very easy.
Cons: Bluetooth STINKS on this unit. The unit won't stay connected to my phone and always disconects and then locks up the unit. I have to constantly load a firmware update sent to me by Garmin to fix the problem only to have it happen again.
Summary: The "keyboard" portion is NOT set up as a traditional keyboard on a computer - rather it is just the alphabet in order - so it makes inputing an address a bit more time consuming. Also, there are some quirks in the directions. If you are in an unfamiliar city, it doesn't always give you enough of a warning of an upcoming turn in enough time to get in proper lane. Also, we recently used it to navigate our way to our hotel in Atlanta, GA.
Pros: Compact, Easy To Read, Strong Construction
Cons: Complicated Controls, Inaccurate, Short Battery Life
Summary: The Garmin nuvi 660 performs all the GPS and other related navigational functions just as well as you would expect for a Garmin product. They are probably the best in that area. As an added bonus, the traffic report functions work well also, although I'm still in the free trial period. The biggest gripe I have is with the FM transmitter function.