We had a Garmin nuvi 350 but lost it in Jan. So got a newer model - the nuvi 275t (Got North america and Europe maps, and free lifetime traffic information). You can select one based on the features and maps you would need.
I swear by Garmin products. We have tried Tomtom and Navigon from friends but I personally find Garmin is much better.
It is very useful especially during winter driving where you cannot see the boards because of snow accumulation. Before buying the GPS we used to take print outs of the route and just keep following it. It was a pain but it worked - until there was some obstruction/diversion and we would have a tough time getting back on track. With the GPS - you wont have to worry about all that.
I never used to drive alone as I am very bad with routes. Now after the GPS, I have started driving my friends out

great improvement for someone like me who cannot find my way back home from a couple of streets away..hehe!
All said, you will find it very useful (more than you think you will use it). Happy GPS shopping