There are, as far as I'm aware, three iterations of the SPOT. The first two being the original spot "puck" and it's sucessor version. What you guys are describing is the SPOT Messenger, the aforementioned third, which requires the use of a smart phone to send messages, track etc.
I think the Messenger, while able to send texts/fb updates, is pretty gimmcky compared to the second edition of the puck, the SPOT Satellite GPS communicator. It fits in the palm of your hand at about 1.5" thick. Simply put it's a waterproof puck with 6 buttons, with it you can send an "Ok" message, a custom pre-written message, log your gps position, you can also send either a "help needed" or an "S.O.S." signal. Most of the messages can be pre-edited, and when you activate them on the SPOT they go to to pre arranged emails and online accounts, with the exception of the "S.O.S." which will also be received/routed to SAR resources who can then use the SPOT to locate you.
I've used a 2nd generation SPOT, the messages need to be activated and left for 5-15 minutes or so, and it can be tricky trying to determine if they've sent or not (I just learned to let them sit for a bit, before carrying on or turning that message off) the track-logging works well, but last I checked the UI limited the # of waypoints you could view simultaeneously, which was a pain.
With a year's subscription it was about $300 CAD for the whole thing.
edit- wanted to add that I think for a rescue professional a proper GPS/Beacon setup would be more useful, but for the rest of us, it adds a resource safetywise that alot of people would otherwise be without.