John Baer wrote a review of SPOT Satellite GPS Messenger on September 19, 2013
Familiarity: I've put it through the wringer
This thing has been spot on accurate for me with over two years of use at least once a month (likely more) in the US and Mexico. I have used the tracking feature, but now just go with the standard subscription. Can send okay's to friends and family, and always have he SOS if I need it, though I haven't to date. If I were going to the big mountains somewhere I would make sure I or someone in my group also had a legit PLB, but for your average weekend warrior hitting the trails or climbing routes in the continental US - this thing is a great option with some more messaging options. MAKE SURE YOU USE LITHIUM BATTERIES, like it says all over the batter compartment as I can tell you from experience you get shotty performance with even the most expensive Alkaline batteries.