Ok, I have to chime in here with my bits and pieces of knowledge... (I used to work for Verizon AND Garmin).

If you are wanting a good navigation system, Garmin is DEFINITELY the way to go. I'm not saying that just because I used to work for them, but because being in the industry, I had the opportunity to test models by all the major manufacturers. Garmin devices have a simple user interface, audible voice guidance, and MANY options in different price ranges. Garmin updates the mapping every 1-2 years and you can purchase map updates to load into the GPS. Unfortunately, new maps aren't free, but they're also not mandatory. If your system is getting you around just fine where you are using it, no need to update every year. The accuracy in Garmin units is top notch. Generally, a Garmin nav system will display your position within 10 feet of accuracy, sometimes even better. The voice guidance is good, very audible, with adjustable volume. As for charges, you pay the one time charge to buy the hardware and there is no monthly service fee. The only other cost you will incur is to purchase the map updates, if and when you choose to do so.

Verizon navigator is fairly new and wasn't around when I worked there, but I have used it and played with it for comparison purposes. The upside is that the maps are all updated by them and you don't have to do any map loading. Now, the downsides. There is a MONTHLY charge for the service, $15 a month if I'm not mistaken. The screen will be very small compared to a stand-alone nav system. Also, the voice guidance is barely audible over road noise. It WILL get you where you're going, but you have to pay attention to your cell phone screen so you don't miss a turn. I think the IDEA of Verizon navigator is a good one, but the execution of the idea is slightly lacking...

Just my