I finally got a chance to put my spot to the test last weekend. Deep in a steep wall canyon it fired out a signal to satellite just fine. My wife got regular updates (Via text message and email) whenever I pushed the "OK" button. I was hopeful it would work in this place (the primary reason we bought it) but to be honest I really didn't expect it to work. Basically down 2000' in a crack in mother earth - so steep the trail switches back and forth on the canyon wall to the bottom. No way you'd ever get a motorized vehicle in there.
Just a few tips. Buy it on ebay - about half retail. Don't buy the tracking subsciption. It's too hard to get into tracking mode and you can;t tell when you've been sucessful very easily. If you want to track just push the OK button once in awhile.
Blow off responsibilities, growing up, and all the boring things in life and do something cool.