"Just hit SOS, we took a big fall and are going to need to be helicoptered out" was the text that I saw from my husband Daniel, while I was halfway up my multipitch climb with my friend Haylee. I looked over at Haylee, told her what was up, and we started thinking up a plan for if/when we needed to try to get them warmer gear and food. Dan was skiing with his partner up by Easy Pass, and Heylee and I were climbing Concord tower, so we were close enough to try to help if needed. Ultimately, the helicopter came fast, evacuated Dan and his partner, and everyone was okay. But being able to communicate in emergencies like that was a great thing to have.
Ultimately, SOS devices like this are generally dead weight and annoying... until you need them. And when you need them, you really need them. For the 3.5 oz that this thing weighs, let me tell you, it's worth it's weight in gold when you're deep out there. Dan and I have also used it to receive weather information when we're out in the backcountry for a long time or in a place with unfamiliar weather patterns (i.e. when we were climbing in the Winds!) This thing is great peace of mind, and if you commonly find yourself deep in the backcountry, I'd recommend it to anyone. We don't tend to rely on it for mapping and navigation however. If you're curious about a device for that, I'd look at the full sized In-Reach.
Pros:
Can literally be a lifesaver
3.5 oz - so light!
Intuitive to use
Can message other In-Reach devices
Connects well to cell phone
Cons:
Monthly fees, but it's worth the monthly cost if you go out frequently, and you can "freeze" it if you need
Doesn't navigate super well on the device itself since the screen is small