I just bought one for the kids and it seems to work reasonably well although a bit inconsistently. Sometimes it seems right on and other times it seems to be way off (and doesn't match my phone's GPS). It is easy for kids to use and my nine-year-old figured it pretty much on her own.
Remember when pricing it, you need to include the cost of the cable ($25). While it includes 250,000 caches, things change over time so you'll need to perform updates. Updating is pretty easy and seems accurate (new caches appeared for us).
