I have one. Mind you, I wasn't the one who purchased it, but if it keeps everyone happy at home, then so be it. It has worked great every time except once. You need to make sure you keep it powered on for about 20-30 minutes after you press one of the buttons (in my case, I've only pushed the "OK" button). I immediately turned mine off after I sent the message and it never got a chance to go through. It needs to be able to keep trying if the first one fails. Other than that, it's a pretty cool, straight forward tool.
The only drawback is that it is making my map case pretty full. SPOT, Compass, altimeter, GPS, map, cell phone, flares, boombox, pint of vodka...