First the good stuff. MapSource Topo is not as expensive as you might think - just over $70 on Amazon.com for the 2008 USA edition. This gives you topo data for the entire country and it’s a steal compared to programs like National Geographic Topo that make you buy each state individually. And unlike National Geo that can only be used on your computer, MapSource maps can be transferred to your GPS so you can take your maps with you on the trail.
MapSource includes all the features most folks will need when working with GPS data - including the ability to cut, combine, and create tracks plus edit and delete individual waypoints and trackpoints. You can even view tracks and waypoints in Google Earth using a simple menu command, though the green triangles that mark your track points are super annoying (you can turn these off in Google Earth). MapSource allows you to export your data in GPX format which is super helpful for transferring GPS data to other programs. Overall Garmin opted to keep things simple and the features they included are useful and solid.