I recently added the Garmin StreetPilot c550 to my arsenal of gadgets. This is one of the nicest bits of consumer electronics I've ever used. It truly is plug-and-play. The UI is brain dead simple. Poke the touch screen with your finger to navigate to points-of-interest, addresses, and intersections. If you want to find the nearest Mexican restaurants, press Where to? > Food > Mexican. A list of the nearest Mexican restaurants will display. The list will update as you drive around so you can do some wardriving for Mexican food. If you press the name of a restaurant you can navigate to it or call it if the c550 is connected to your mobile phone via bluetooth. This hands-free calling is pretty nifty. With the press of a finger you can call the phone numbers for any of the included points-of-interest. You can program a call home number as well. If your phone supports it, you can access your phone's address book from the c550. The address book of my Blackberry 8700c shows up just fine. Incoming calls are displayed with your phone book information to provide better caller identification.
The c550 integrates an FM TMC traffic receiver. If your area provides traffic information, the c550 can display traffic alerts and route around congestion. This has worked pretty well for me in San Jose. A list of congested areas is displayed, and the c550 will route around them at my request.
The map can be panned by dragging your finger. You can then set a pointer on a location on the map and click "Go" to navigate to that point. Pretty slick.
The turn-by-turn voice prompting is clear and intelligible. You can choose a number of synthesized voices in various languages. "Jill" handles American English navigation. Jill hasn't led me astray yet.
The suction cup windshield mount hasn't accidentally released on me yet. It seems sufficiently sturdy to keep the c550 attached to the windshield and angled to your liking. If you live in California, it is illegal to attach things to the front windshield. I ignore such silly, intrusive laws, but if you're worried about Johnny Law, an adhesive plate is provided that will allow securing the c550 to your dash.
The c550 is full of nice conveniences and the interface is simple and lucid. So far I'm loving it.