I've had a Garmin 60CS for about 6 or 7 years and love it. I love the idea of tapping into all this incredible, almost science fiction, satelite technology. I love the interface with Google Earth, planning routes in advance on my computer and transfering them to my GPS - or vice-versa. But it is a gadget.
It doesn't replace good field skills if you are in remote areas. It doesn't make coffee on a cold morning or keep the beer cool on a warm afternoon. Unlike a compass, if the batteries run down, it's useless. All it does is give and store your positions - here in Chile to about 7 metres accuracy (better in the US, I think) - or the tracks you follow.
Models such as the one you are looking at have maps which either come with the GPS or can be downloaded through the computer.
How good these maps are doesn't depend on the machine - but on what the company or other suppliers offer. These electronic maps are generally not interchangeable between brands. Nor can you easily generate your own maps by, for example, scanning a paper map.
So a very important consideration is the availability of electronic maps for your area of use and brand of GPS.
Memory, too, can be an issue if you want to store several detailed maps for different areas. Although mine doesn't, the latest models have ports for additional memory chips.