The Garmin Nuvi 660 could be considered as one of the most popular portable GPS navigation available on the market.
Display
The Nuvi 660 features a now-becoming-standard 4.3" LCD touchscreen display. It's quite bright and easy to see in broad daylight, giving drivers highly visible on screen navigation in any lighting condition. It is also in widescreen resolution, capable of displaying 480 x 272 total pixel resolution. The unit is still considerably thin at just under an inch (0.9"). In addition, the unit weighs only 6.2 ounces so you can stick it in your pocket or take it with you wherever you go.

Navigation Features
Although Garmin claims to feature a large amount of POIs (Points-of-Interests), they never specified the exact amount of POIs it actually features. The problem here is then the difficulty you may have trying to compare and contrast between different units. Some customers have reported that to get an additional 6 million POI, users would need to purchase an additional add-on from Garmin in order to have the POI database. In addition, many have also reported that current gas stations and other points of interests have not been added to the Nuvi 660. Unfortunately, this presents a large problem for those who travel often to unfamiliar areas. But if you're just a common traveler, POIs may not even be significant for you. In addition, the Nuvi 660 could receive local traffic information and capable of displaying traffic hotspots nearby to your location. This is a great feature to have if you live in densely populated metropolitan areas, where traffic could always be a problem.

Media Compatibility
The Nuvi 660 does have a built-in MP3 player, audiobook playback, as well as a built-in picture viewer. Garmin designed the unit with purely navigation in mind, not media playback. However, the unit does feature an integrated FM transmitter that allows you to playback audio files into your existing FM radio in your vehicle. This means no messy wires connecting your GPS unit to your in dash receiver.

Built-in Bluetooth
If you live in California, this coming summer you may be in trouble. The law requires that drivers DO NOT speak on a cellular phone while operating a motor vehicle. For each offense, a driver could receive a $50 ticket, plus $100 additional fine for any repeated offense. The solution is Bluetooth interface, which is featured in the Garmin Nuvi 660. The unit is capable of displaying received call information, which may include phone numbers and phonebook names (if your phone is capable). You could speak hands-free with its integrated microphone and you could even make phone calls by using its touchscreen numbers. This is an excellent feature to have in order to maintain concentration and safety on the road. The Garmin Nuvi 660 is an excellent GPS Navigation, but some may say it's a bit overpriced at more than $320 for features that is increasingly becoming standard. But it does boast a 5-hour battery life, which is considerably longer than most GPS units out there. It does have Bluetooth and some media playback, but if you're a media junkie, you may want to pass since it only plays MP3s and audiobooks.