I've got the Lowrance 500c as well. Bought it specifically for the large bright 5-inch screen that sits right on top of the dash. When I'm in traffic, I don't want to be taking my eyes off the road to decipher one of those tiny screens that come with most GPSs. With the big screen, you can zoom out and have a very large area that's readable so you can "see" miles ahead.
The only thing it's missing is real-time weather and traffic built in. There's a few out there that have it, but that will be standard on nearly all of them within a year or so.
Another thing that's cool with these is when you're driving in snow or fog and can't see the road, you put it in 3D mode and you can see which way the road is curving ahead or if there are cross streets coming up as you drive - sort of like flying IFR!
